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AMERICAN
JOURNAL OF SCIENCE.
Epirorn: EDWARD S. DANA.
ASSOCIATE EDITORS
Proressorss GEORGE L. GOODALE, JOHN TROWBRIDGE,
W. G. FARLOW anp WM. M. DAVIS, or Camsringe,
Proressorss ADDISON E. VERRILL, HORACE L. WELLS,
L. V. PIRSSON anp H. E. GREGORY, or New Haven,
Proressor GEORGE F. BARKER, or PHILADELPHL,
Proressor HENRY S. WILLIAMS, or ItHaca,
Proressor JOSEPH S. AMES, or Battimore,
Mr. J. S. DILLER, or Wasuineron.
FOURTH SERIES
VOL. XX VITI—[W HOLE NUMBER, CLXXVIII.]
WITH TWO PLATES.
NEW HAVEN, CONNECTICUT.
MS MONS! ¢
2OASAS
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THE TUTTLE, MOREHOUSE &
ti ord NEW HAVEN. —
CONTENTS TO VOLUME XXVIII.
INGUREY oo Sao.
Art. I.—On the Magnetic Properties at High Excitations of
a Remarkably Pure Specimen of Soft Norway Iron; by
LS. (Ub UEAMGKONDIES Si Sege DNSip gmp aeate 9c Ca ir os eo ent Bee
II.—Notes on some Rocks from the Sawtooth Range of the
Olympic Mountains, Washington ; by R. ARNoLD~..---
Il].—Analysis of the Mineral Neptunite from San Benito
Seanty. Caliearmias by W. M. BRADLEY... 4. 205-02) .
1V.—Turtles from Upper Harrison Beds; by F. B. Loomis. -
we Pyrosenetic Npidote ; by B.S. Burter ...-.-.. -.-- --
VI.—Gravimetric Determination of Free Iodine by Action of
Metallic Silver; by F. A. Goocu and C. C. Perkins...
Vil.—Pyromorphite from British Columbia, Canada ; by O.
OMNIS pers seers LS Ue Ee ee See
VIIIl.—Application of the Term Laramie; by A. C. Peatz-
1X.—Descriptions of New Genera and Species of Starfishes
from North Pacific Coast of America; by A. HK. VeRrRIL1
X.—Rare Rock Type from the Monteregian Hills, Canada ;
Renmei rss. sho ee Le Pe Cra a oe
SCIENTIFIC INTELLIGENCE.
Page
9
15
17
27
30
40
45
ae
Chemistry andPhysics—Cuprous Sulphate, A. Recoura : Action of Hydrogen
Antimonide upon Dilute Silver Solutions, H. RECKLEBEN, 74.—Separation
of Antimony and Tin, G. Panoyotow: Purification of Sulphuric Acid by
Freezing, ee aa 7o.—Heat of Formation and Stability of Lead and
Silver Compounds, A. Cotson: Refraction of Réntgen Rays, B. WALTER and
i. POL : Polarization of Rontgen Rays, J. HeRweEe : Absorption of the
y-Rays of Radium a Lead, Y. TA OMIKOSKI, 76.—Use of Zine Sulphate in
the Braun Tube, _GIESEL and J. ZENNECK, 77.—Luftelektrizitat, A.
GocKEL: La ee Radiante ei Raggi Magnetici, JN, desGasiil S Textbook
of Sound, E. H. Barton, 77.—Applied Mechanics for Engineers, E. L.
Hancock: Absorption Spectra of Solutions, H. C. Jones and J. A.
ANDERSON, 78.—Electricity, Sound and Light, R. A. Mituixan and J.
Mitts: Kinfthrung in die Elektrotechnik, C. Hrmnke: La Machine a
Influence, son Evolution, sa Théorie, V. SCHAFFERS, 79.
Geology and Natural History— Publications of the United States Geological
Survey, G. O. SmitH: Geological Survey of Canada, R. W. Brock, 80.—
Geological Survey of Western Australia, H. P. Woopwarp: New Zealand
Geological Survey Department: Mineral Survey of Ceylon, 81.—Mineral
Resources of Virginia, T. L. Watson: Minerals of Arizona: Das Salz, dessen
Vorkommen und Verwertung in Samtlichen Staaten der Erde, 82.—Brief
Notices of some Recently Described Minerals; 883.—Guide dans la Collec-
tion des Météorites avec le Catalogue des Chutes représentées au Museum :
Mendel’s Principles of Heredity, 84.—Contributions from the Gray Herba-
rium of Harvard University : Elemente der exakten Erblichkeitslehre,
80.
Miscellaneous Scientific Intelligence—Publications of the U.S. Coast and
Geodetic Survey, 86.—Hypsometry: Precise Leveling in the United States,
1903-1907: Bureau of American Ethnology, Smithsonian Institution :
Museum of the Brooklyn Institute of Arts and Sciences: Report of
Pro-
ceedings of the American Mining Congress: Publication of the Works of
Amedeo Avogadro, 87.—Proposed Publication of the Works of Leonhard
Kuler: Prizes offered by the Austrian Society of Engineers and Architects:
Psycho-Biologie et Energetique, Essai sur un Principe des Méthodes intui-
tives de Calcul: Die Einheit des physikalischen Weltbildes: Phrenology
or the Doctrine of the Mental Phenomena, 88.
lv CONTENTS.
Number 164.
Page
Arr. XI.—Electric Arc between Metallic Electrodes ; by
W.G. Capy and G. W. VINAL.-__ 127 ae 89
XII.—Heat of Formation of Trisodium Orthophosphate,
Trisodium Orthoarsenate, the Oxides of Antimony, Bis-
muth Trioxide; and fourth paper on the Heat of Com-
bination of Acidic Oxides with Sodium Oxide: bx
W. G. Mixter 2.002. 22 S2e2 eae 2a. 2. 2 Sr
XITI.—Quantitative Precipitation of Tellurium Dioxide and
its Application to the Separation of Tellurium from
Selenium ; by P. E. Brownine and W. R. Furr ____- 112
XIV.—Coloration in Peroxidized Titanium Solutions, with
Special Reference to the Colorimetric Methods of Esti-
mating Titanium and Fluorine ; by H. E. Merwin.__- 119
XV.—New Fossil Coleoptera from Florissant; by H: F.
WICKHAM ©2252. 2502 Se Ae ial 126
XVI.—Lighthouse Granite near New Haven, Connecticut ;
by F. Warp 220.225.222.072 Se 131
XVII.—Silurian Section at Arisaig, Nova Scotia; by W. H.
“TWENHOFEL -. 222. 2200222222004 0 ee
XVIII.—Fish Fauna of the Albert Shales of New Bruns-
wick; by. L, M. Lampn (22 2.2.22 25) 165
XIX. Stan Dust on the Benes Sea Ice Floes; by ~
E.:M. Kinpun._....2 2.22 82255522 175
XX.—Modification of Lavoisier and Laplace’s Method of
Determining the Linear Coefficient of Expansion; by
S: BR. WiiiaMs 2.3.0 22 ee ee eee 180
XXI.—New Proboscidean from the Lower Miocene of
Nebraska; by H. J. Cook ..... ...._ 22) 2223
XXII.—Mineral Notes from the Mineralogical Laboratory
of the Sheffield Scientific School of Yale University ;
by W. E. Forp, F. Warp and J. lL. Pogue esa 185
SCIENTIFIC INTELLIGENCE.
Geology—Tidal and Other Problems; Contributions to Cosmogony and the
Fundamental Problems of Geology, T. CO. CHamBEruin, ete., 188.—
Second Appendix to the Sixth Edition of Dana’s System of Mineralogy,
E. S. Dana and W. E. Forp: Sketch of the Mineral Resources of India,
T. H. Hottanp: Igneous Rocks: Composition, Texture and Classification,
Description and Oceurrence, J. P. Ippines, 196.
Obituary—Simon Newcome, 196.
. CONTENTS. Vv
IN GH ber: L65:
d Page
Arr. XXIII.—Physiography of the Central Andes: I.
mie Maritime Andes’: by I. BowMAN - 2.22.22. 2/38. 197
XXIV.—Geology and Structure of the Ancient Vol-
eanic Rocks of Davidson County, North Carolina, by
Mere inh ima = 2 cS eR EEE 218
XXV.—Electric Arc between Metallic Electrodes; by
Pecan enoy: ob hird: paper) 2: 2 ob bo eae 239
XXVI.—Initial Velocities of the Electrons Produced
beetilsra- Violet Lisht ; by A.W. Hur. 22-2222) 0222 Dont
XXVII.—New Declination Instrument ; by C. C. Hurcuins 260
XXVIUI.-—Relation between the Refractive Index and
the Density of some Crystallized Silicates and Their
(2 SEREGS ETD E RS ae DP. SD ae a a RR cp 263
XXIX.—Note on the Miocene Drum _ Fish—Pogonias
meemacntatus (Cope); by B..SmMirins.2. 22.2222... 22 275
XXX.—Description of ‘Tertiary Insects, VIL; by T.
ere OCRE NE i es ee see a a 283
XXXI.—Method for the Iodometric Determination of
Silver Based upon the Reducing Action of Potassium
mee oy bt. BOSWORTH. 22242 0:. 22... 52222242: 287
SCIENTIFIC INTELLIGENCE.
Obituary—Si1mon Newcome, 290; SAMUEL WILLIAM JOHNSON, 292.
al CONTENTS.
Number 166.
Page
Arr. XXXIL.—Binary Systems of Alumina with Silica,
Lime and Magnesia; by E. 8S. SHepHerpD and G, A.
Rankin. With Optical Study, by F. E. Wricar __--- 293
XX XIII.—Specific Heats of Silicates and Platinum ; by W.
P. WHITE 3... 2b eal eo) i ere
XXXIV.—Complexity of Tellurium; by P. E. Brownine
and W.R. FLINT 9222 02.222 ee 847
XXXV.—Arizonite, Ferric Metatitanate; by C. Patmer_.. 353
XXXVI.—Retardation of Alpha Rays by Metals and Gases;
by T.S: Tayvnor 220. ..25 2.85 24 22 er 857
XXXVII.—Physiography of the Central Andes: IL The
Eastern Andes; by I. Bowman ____.__2_2....255 ees
XXX ViIL—New Species of Teleoceras from the Miocene of
Nebraska; by IT. F. OQtcotr .__...-..-.. 2 408
SAME NVGILLbANM JOHNSON@Eo 0. 5 20a eee
SCIENTIFIC INTELLIGENCE.
Chemistry and Physics—New Method for the Determination of Iodides and
Free Iodine, BuGArsKy and HovratH : Chemical Action of the Penetrat-
ing Rays of Radium upon Water, M. Kernpaum, 408.—Decomposition of
Water by Ultra-violet Rays, M. KernBAum: Radio-activity of Potassium
Salts, Henriot and Vavon : Cementation of Iron by Charcoal ina Vacuum,
GUILLET and GriFFITHS, 409.
Geology— Devonian Faunas of the Northern Shan States, F. R. CowPrEr
ReEpD: Osteology of the Jurassic reptile Camptosaurus, C. W. GILMORE,
410.—Systematic relationships of certain American Arthrodires, L. Hus-
SAKOF: Revision of the Entelodontide, O. A. PETERSON: New Species of
Procamelus from the Upper Miocene of Montana, E. DoucLass: Notes on
the fossil mammalian genus Ptilodus with descriptions of new species,
J. W. Giputey, 411.—Descriptions of two new species of Pleistocene
ruminants of the genera Ovibos and Boétherium, J. W. GipLey, 412.
Miscellaneous Scientific Intelligence—British Association for the Advance-
ment of Science: Hinftthrung in eine Philosophie des Geisteslebens, R.
Kucxken, 412.
CONTENTS. vil
Number 167.
Page
Art. XX XIX.—Vesuvius: Characteristics and Phenomena
of the present Repose-period ; by F. A. PErrer. With
Peeper tte ee > emerge, Oe ro a
XL.—Great Nevada Meteor of 1894; by W. P. JENNEY..__ 431
XLI.—Phenomena of the Electrolytic Decomposition of
Hydrochloric Acid ; by F. A. Goocu and F. L. Gatss.. 435
XLII.—Eocene Fossils from Green River, Wyoming; by
Beer COCKE E a5 2 sa ee SL AAG
XLII.—Note on the Occurrence of an Interesting Pegma-
tite in the Granite of Quincy, Mass.; by C. H. Warren 449
XLIV.—Melting Point Determination ; by W. P. WuirE_- 453
XLV.—Melting Point Methods at High Temperatures ; by
Ns EP UNTESTED 1s cE Tae es we ge ee 474
XLVI.— Existence of Teeth and of a Lantern in the Genus
Echinonéus Van Phels; by A. Acassiz. With Plate II 490
SCIENTIFIC INTELLIGENCE.
Chemistry and Physics—Separation of Titanium, Niobium and Tantalum, L.
Wetss and M. LANDECKER, 493.—Electrical Discharges from Radium Ema-
nation, DEBIERNE: Outlines of Chemistry, L. Kantenprere, 494.—The
Fundamental Principles of Chemistry, W. Ostwatp: Elementary Modern
Chemistry. W. OstwaLp and H. W. Morse: Resistance due to Obliquely
Moving Waves, etc., LorD RAYLEIGH, 495.—Excitement of Positive Rays
by Ultra-violet Light, H. DemBer: Electricity excited by the Fall of
Mercury through gases upon the surfaces of metals, A. BECKER: Viscosity
of Gases, Gy. ZEMPLEN, 496.
Geology—Geology of the Queenstown Subdivision, J. ParKx, 497.—West Vir-
ginia Geological Survey, I. C. Wurre, 498.—Geological Survey of New
Jersey, H. B. KtmMe c: Relations between local magnetic disturbances
and the genesis of Petroleum, G. F. BeckEr, 499.—Production of Coal in
1908 : Carnivora and Insectivora of the Bridger Basin, Middle Eocene, W.
D. MatrHew: Pliocene Fauna from Western Nebraska, W. D. MaTrHew
and H. J. Coox, 500.—Vertebrata of the Oligocene of the Cypress Hills,
Saskatchewan, L. M. Lampe: Commissdo de estudos das Minas de Carvao
de Pedra do Brazil, J. H. MacGrecor: Skull and Dentition of an extinct
Cat closely allied to Felix atrox Leidy, J. C. MerrR1IAm: Teratornis, a new
Avian Genus from Rancho la Brea, L. H. MILurr, 501.—Igneous Rocks ;
Composition, Texture and Classification, J. P. Ipp1nes, 502.—Natural
History of Igneous Rocks, A. HARKER, 505.—Journeys through Korea, B.
Koro, 504.
Miscellaneous Scientific Intelligence— Darwin and Modern Science, 505.—Zoo-
cécidies des Plantes d’Europe et du Bassin de la Mediterranée, C. Houarp:
Autogamie bei.Protisten und ihre Bedeutung fir das Befruchtungsprob-
lem, M. Hartmann: Observations Méridiennes, F. Boguet, 506.—Ostwald’s
Klassiker der Exakten Wissenschaften : Catalogue of the Lepidoptera Pha-
leenz in the British Museum: Les Prix Nobel en 1906, 507.
Obituary—Dr. JOSEPH FREDERICK WHITEAVES: HuGH FLETCHER : Dr. ANTON
Dourn, 508.
Vill CONTENTS.
Number 168
Page
Arr. XLVII.— Ordovician and Silurian Formations in Alex-
ander County, Illinois; by IT. BH. SAVAGE 5222 3ae eee 509
XLVIII.—Section at Cape Thompson, Alaska; by EH. M.
KINDLE... 22.2.2. ee elo. ee 520
XLIX.—New Method of Measuring Light Efficiency ; by
C.C, dIGTCHINS 5220 2925. 529
L.—Three New Fossil Insects from Florissant, Colorado; by
S.A. RoWWER. 1.22. .2- oe sl ee 533
LI.—Connellite and Chalcophyllite from Bisbee, Arizona; by
C.-PavacHE and H. EH. Merwin 22. 0.222.433 oi
LII.— Optical Properties of Hastingsite from Dungannon,
Hastings County, Ontario; by R. P. D. GrawAm.__-__- 540
LUI.—Electrolytic Determination of Chlorine in Hydro-
chloric Acid with the Use of the Silver Anode; by F. A.
Gooca and .H. L. Reap __...i.2221...... 2
SCIENTIFIC INTELLIGENCE.
Chemistry and Physics—Boiling Points of Metals, H. C. GREENWOOD :
Sodium Alum, W. R. SmirH, 553.—The Elements of Metallography, Dr.
R. Ruger: Outlines of Chemistry with Practical Work, H. J. H. FENTON:
An Elementary Treatise on Qualitative Chemical Analysis, J. F. SELLERS ;
A Manual of Qualitative Chemical Analysis, J. F. McGrecory: The
Periodic Law, A. E. GARRETT, 504.—A Text-Book of Physical Chemistry,
Theory and Practice, A. W. Ewetut: A Text-Book of Physiological Chem-
istry, J. H. Lona: Positive Rays. W. Wien: Apparent fusion of Carbon
in the Singing Are and in Sparks, M. La Rosa.—Determination of ¢/m,
K. Wouz: Spectroscopie Astronomique, P. SALET: Text-Book of Physies,
A. W. Durr, 556.—General Physics : Mechanics and Heat, J. A. CULLER,
D907.
Geology—Publications of the United States Geological Survey, G. O. SMITH,
507.—Indiana, Department of Geology and Natural Resources; Thirty-
Third Annual Report, W. 5S. BuatcHtEy: Colorado Geological Survey,
R. D. Georce: Geological Survey of Michigan, A. C. Lanz, 559.—Illinois
Geological State Survey, H. F. Barns: History, Geology and Statistics of
the Oklahoma Oil and Gas Fields, E. R. Perry and L. L. Hurcnison :
Les Variations Periodiques des Glaciers, XIII Rapport, 1907, Ep. Bruck-
NER et E. Murer, 560.—Hand Book for Field Geologists, C. W. Hayus :
Crinoids of Teunessee, EK. Woop: Dendroid Graptolites of the Niagaran
dolomites at Hamilton, Ont., R. S. Basster, 561.—Carboniferous fauna
from Nowaja Semlja, G. W. Lex: Vorliufige Mitteilung tber das genus
Pseudolingula, A, Mickwirz, 562.—Clay-Working Industry in the United
States, H. ‘Rres and H. Letcuton: Elements of Mineralogy, Crystallogeaeay
and Blowpipe Analysis, A. J. Moses and C. L. Parsons, 563,
Miscellaneous Scientific Inielligence—National Academy of Sciences, 563.—
Carnegie Institution of Washington, 564.—Harvard College Observatory,
E. C. PickertnG: Allegheny Observatory of the University of Pittsburgh:
Museum of the Brooklyn Institute of Arts and Sciences : The Story of the
Comets, G. F. CHAMBERS: Mars et ses Canaux; Les Conditions de vie,
LoweLL-Moyen, 565.—Manual for Engineers, C. EH. Frrris: Wood
Turning, G. A. Ross; Sir Joseph Banks, ‘‘ The Father of Australia,” J. H.
MAIDEN: American Association for the Advancement of Science, 566.
INDEX, 567.
VOL. XXVIII. JULY, 1909.
| ‘Established by BENJAMIN SILLIMAN in 1818.
THE
AMERICAN |
JOURNAL OF SCIENCE.
|
Epirorn: EDWARD §. DANA.
ASSOCIATE EDITORS
Proressors GEORGE L. GOODALE, JOHN TROWBRIDGE,
W. G. FARLOW anp WM. M. DAVIS, or Camarwcz,
PROFESSORS ADDISON E. VERRIUL, HORACE L. WELLS,
L. V. PIRSSON anp H. E. GR IGORY, or New Haven,
|
|
:
|
| Proressor GEORGE F. BAKER, or ae
_ Prorusson HENRY S. WILLIAMS, or Iruaca, _
Proresson JOSEPH S. 1MES, or Barrmorz,
Mr. J. S. DILLER, or Wasuineton.
.
'
FOURTH SERIES
VOL, XXVIII-! WHOLE NUMBER, CLXXVIII_]
No. 163—JULY, 1909.
NEW HAVEN, CONNECTICUT.
190-9..
THE TUTTLE; MOREHOUSE & TAYLOR CO., PRINTERS, 123 TEMPLE STREET.
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IMPORTANT NEWS
We have secured a collection of exceptionally fine minerals collected by
an American professor of national repute ; it is beyond doubt the finest col-
lection we have yet handled. It consists of eight large cases of minerals all
of which are fine. Lists are in preparation and will be sent only on appli-
cation.
A REMARKABLE CERUSSITE
We have on exhibition the largest and finest twin Cerussite in the
world. All its planes are finely developed. The crystals measure 7 inches
in length, 344 inches in width, and is 14 inch in thickness. The erystal is
transparent, and its structure is beautifully displayed. Photo and partic-
ulars on application.
A WONDERFUL SPECIMEN OF GOLD
We have secured from the owners a wonderful specimen of gold,
from a Nevada mine. It is 314 x 234 x21¢ inches in size and shows a solid
vein of gold 1 inch in thickness all the way through the specimen. It is
beyond doubt the richest specimen for its size in the world. It weighs 2024
ounces. The matrix itself is a rich ore of gold. One side of ees is
polished. Price $500.00.
AN INTERESTING COLLECTION OF SEMI-
PRECIOUS STONES
We secured from a bankrupt sale of a well-known eastern concern
whose specialty was the cutting and polishing of stones for mineralogists a
unique lot of cut semi-precious stones of unusual beauty and rarity. They
must be seen to be appreciated. They have been priced so low that
the prices do not tell the tale. We name a‘few below; they run from-
50c. to $2.50 each: unycite, perthite, aventurine, greentrap cinnabar, thulite,
Sunstone, moonstone, amazonstone, chrysoprase, green chalcedony, sodalite.
labradorite, malachite, azurite, jade, turquoise, ruby matrix, emerald
matrix, rose quartz, lapis-lazuli, jasper, agate, moss agate, carnelian, moss-
opal, bloodstone, thomsonite, chlorastrolite, dumortierite, dioptase, the
latest, from Congo, at, $1.50 per e., and all other known semi-precious stones.
IMPORTANT NOTICE
It has been usual for the past four years to offer special inducements to
visit us during the summer months. In order to do this, with little expense
to yourself, we offer you a 10 per cent discount on rare and polished minerals
and cut gems and 20 per cent on ordinary mineral specimens. This enables
you to pay your traveling expense with the discount on your bill. If you
are unable to visit us and see our wonderful display, write us what you are
interested in, and we will send you a box on approval. We prefer to be
busy, even if we have to divide our profit with you. Do nct delay, but
write or call on us at once.
If you have not yet received our new 12-page mineral and 10-page gem
circulars, write us and we will send them at once,
Agr. PEPE REV,
81—83 Fulton Street, New York City.
THE
AMERICAN JOURNAL OF SCIENCE
PRO UR Tit sk RIES .:]
+o
Arr. 1—On the Magnetic Properties at High Kxcitations
of a Remarkably Pure Specimen of Soft Norway Lron ;
by B. Oseoop Prtxce.
SomE mouths ago an electro-magnet was made for special
use in the Jefferson Laboratory which had the form of a toroid
uniformly wound with insulated wire for nineteen-twentieths
of its perimeter. The core was of stout iron rod bent into the
shape of a ring—complete except for a gap one centimeter
wide. The mean diameter of the core was about fifty centi-
meters and a meridian section of the iron had an area of about
twenty square centimeters. The exciting coil was made of
about thirty kilograms of No. 10 B. & 8. wire and the magnet
had the general appearance indicated by figure 1, although the
turns of wire which show im the photograph belong to a short
test coil outside the winding proper.
It is evident that, under the most favorable circumstances,
the leakage in the case of a magnet of these dimensions must
be very large, but when this magnet was tried its performance
fell so far below what, according to any known experience, it
ought to have been, that it was thought best to have the iron
tested both chemically and magnetically in the hope that the
information thus procured might prove valuable in future
designing. This seemed the more desirable since the core had
been obtained by Professor Trowbridge, the Director of the
Laboratory, in response to his inquiry for the very best brand
of soft Norway iron to be had in the market. |
The chemical analysis made by Mr. Emile Raymond Riegel
showed this commercial iron to be of an extraordinary purity.
The tests for nickel, cobalt, manganese, tungsten, and for
“Groups IV and V” were all negative. There was less than
0°03 per cent of carbon, less than 0°047 per cent of phos-
Am. Jour. Sci.—FourtH Srerins, VoL. XXVIII, No. 163.—Juny, 1909.
1
2 Peirce—Magnetic Properties at High Kxcitations.
phorus, less than 0°03 per cent of silicon, and less than 0:003 .
per cent of sulphur. The iron dissolved ‘violently in shghtly
diluted HNO,, and when the residue had been dissolved for
carbon, a mere discoloration of the beaker remained.
There was nothing, therefore, in the composition of the iron
core to account for the comparative uselessness of the magnet.
Hires ae
The response of this remarkable iron to magnetic excitation
was equally satisfactory, and the present report describes
briefly determinations of the permeabilities of two pieces of it
under very strong magnetizing fields. The work was done by
Mr. John Coulson and myself, and was extremely troublesome
because only a short stout piece of the iron used in making
the core was available. From this a rod 1:26 centimeters in
diameter and about 30 centimeters long was turned by Mr.
Peirce—Magnetic Properties at High Excitations. 3
G. W. Thompson, the mechanician of the Jefferson Labora-
tory, and this rod was tested in various ways in the yoke rep-
Bigs 2:
resented in figure 2. Jaws of various shapes were tried
and different ways of making the joints between the jaws and
4. Peirce—Magnetic Properties at High Excitations.
the test piece. Usually under strong magnetic excitation,
between the jaws of the yoke, there was a sensible leakage of
lines of induction through the surface of the specimen into the
wir, and the field in the air about the rod was far from uniform
in any available portion. We found eventually, however, that
if a piece of the rod of about 80 millimeters free length, with
tapered ends, was inserted into holes in the ends of the conical
jaws represented in figure 3, the lines of force in the air just
about the specimen near its center were for a considerable
distance practically parallel to the axis of the rod and that the
value of /7 in the air in this region was sensibly equal to the
value of the same quantity in the rod.
Fie. 3.
After a specimen of this standard length had been accurately
fitted to the jaws by Mr. Thompson, the central portion of the
iron rod was given a very thin coat of shellac varnish and two
test coils, each consisting of twenty turns of very fine well
insulated wire, were wound side by side in a single layer over
the rod and these extended over rather more than a centimeter
of the length of the specimen near its center. These coils were
first tested against each other to find out whether they were
practically alike, and then—if this condition was satisfied—both
together in series formed the inner test coil (K). The outer
test coil (L) was wound in a single layer on a very thin
shell of boxwood which had eae seasoning for many years.
After corrections had been made for the thickness of the wire
of the test coils and of its insulation, it was possible .to com-
pute from the measured change of induction flux through
Peirce—Magnetic Properties at igh Excitations. 5
_K and L due to a reversal of the current in the exciting cireuit
of the yoke, corresponding values of 7 and B.
The ballistic galvanometer used in this work had a period
so long that no appreciable error was caused by the fact that
several seconds were necessary to bring about a complete
reversal of magnetization in the magnetic circuit. The gal-
vanometer has been described under the letter V, in the Pro- -
ceedings of the American Academy of Sciences in December
of last year.
The test coils were wound by Mr. Coulson, who has helped
in all thé work.
_ The iron of which the magnet core described above was
made is here denoted by the letter P, while Q denotes a similar
very pure specimen of Norway iron obtained from a new
source.
Taste I.—Specimen of Norway Iron (P) Magnetized in Massive
Yoke.
(Free length about 80 millimeters, diameter 12°67 millimeters.)
H B I
150 19160 1513
200 19920 1566
300 21040 1650
400 21660 1692
500 21920 1705
600 22130 1713
.700 22300 1720
800 22450 1723
1000 22720 1729
1200 22940 1730
1400 23180 1781
1600 23380 17382
2000 23780 17338
2500 24280 1733
The maximum value of / seems to be in the vicinity of
1733, and for large values of the excitation corresponding
values of H and B may be computed by means of the equa-
mionris—— 7 21780.
This record shows conclusively that the magnetic perme-
ability of this iron under strong excitation is extraordinarily
high and that the failure of the magnet mentioned at the
beginning of this report was not due to poor material in the
core. The real source of the difficulty is disclosed by an
examination of the diagram shown in figure 4. This was
obtained by sprinkling iron filings upon a horizontal piece of
cardboard which rested on the toroid as it lay upon the floor
¢
+ °
6 Peirce—Magnetic Properties at High Hacitations.
and earried a heavy current. Although the cardboard was not
favorably placed, there are evidences that at least ten con-
sequent poles were created between the ends of the core when
it was strongly excited. When the exciting current was
reversed these poles changed sign, but in many places outside
the exciting coil the direction of the field was always opposed
to what it would be if these consequent poles did not exist.
This core has been annealed as well as the maker could do
lene, 2!
WW ey fe ode
22 SEE SERRE NII
Ses S \ j A = S WY LZ, Zi
if
BSS
Ss
~S ==
SSS S
5 ~ : =
= es = ye,
SL tf
BZ — SS hy
it, after it had been bent into shape, but the process demands
great skill and, as is well known, soft Norway iron is very likely
to acquire slight differences of temper due to unequal heating
in the forge fire.
Table II exhibits the results of some observations made-
upon a half-inch rod of Norway iron (R), when magnetized
in a uniformly wound solenoid. The rod was about ten feet
Peirce—Magnetice Properties at High Excitations. 7
long. When it was purchased this iron was very soft as is
shown by the numbers in the second column, which give the
values of the induction (4) corresponding to the values of
in the first column. When, however, the rod had been again
subjected by Mr. Thompson to an elaborate annealing process,
its permeability had been somewhat increased as appears from
the values of #& exhibited in the third column.
TasLe I].—WNorway Iron Rod (hk) Magnetized in the Long
Solenoid.
(Length about 300 centimeters, diameter 12°67 millimeters.)
vee B B
(Before the iron had (After the rod had
been annealed.) been annealed.)
9) 12400 12560
10 14800 14940
14 15460 15540
20 15960 16040
30 16400 16520
40 16650 16920
50 16920 17220
60 17180 17450
70 17400 17630
80 17600 _ 17820
100 17940 18210
Specimen Q, like specimen P, was cut from a bar of the
best Norway iron two inches in diameter, but the two bars
came from different dealers. These irons seem to be nearly
alike in temper and in composition.
Taste II]—Specimen of Norway Iron (@Q) Magnetized in
Massive Yoke.
(Free length about 80 millimeters, diameter 12°67 millimeters.)
ED B /E
300 20530 1610
400 21110 1648
600 22020 1704
700 22300 Ie)
800 22510 1728
1000 22800 1735
1200 23020 1737
1400 23240 1738
1650 24240 1738
2000 23840 1738
2400 23490 1738
8 Peirce— Magnetic Properties at High Excitations.
From H=1100 up to /7=2450, the observed values of 7
differ on the average from their mean by about one-sixth of
one per cent only.
For high excitations, corresponding values of 7 and B may
be obtained from the equation B= H+ 21840.
Table IV shows the results of some determinations of the
maximum value of / made upon an isthmus piece of the iron
P after it had been subjected to an annealing process lasting
about 48 hours and was therefore extremely soft.
TasLe 1V.—Specially Annealed Isthmus Piece of Norway Iron
(2).
(Cross section of isthmus 0°2050 square centimeters; mean area of inner
test coil 0°2230 square centimeters ; mean area of outer test coil 0:5020
square centimeters. )
Exciting Current A B I
1°00 5920 28580 1799
4°07 12370 34900 1794
5'58 13720 36210 1790
9°90 16000 38530 : 1793
23°00 18130 40780 1802
31°00 18810 41400 1797
For a current of about 55 amperes a value B—42200 was
reached but the current fell so rapidly that HZ could not be
accurately determined. In this case the excitation was upwards
of 160,000 ampere-turns.
It is interesting to compare this remarkable value for the
maximum intensity of magnetization with that obtained for a
specimen of the iron R, after it had been thoroughly annealed.
Taste V.—Annealed Norway Iron (fh) in Massive Yoke.
(Free length about 80 millimeters.)
H B If
800 22770 1748
900 22880 1749
1000 23000 1750
1500 23500 1751.
1800 23810 1751
2000 24010 1751
2350 24360 1751
The Jefferson Laboratory, Cambridge, Mass.
R. Arnold—Rocks from the Sawtooth Range. 9
Arr. II—Wotes on some Rocks from the Sawtooth Range
of the Olympic Mountains, Washington;* by Raipx
ARNOLD.
Prosasty less is known about the geology of the Olympic
Mountains, Washington, than of any other equal and important
area in the United States.t For that reason the writer was
particularly interested in a small collection of rocks from one
of the important but little known ranges of this great moun-
tain group, recently received from Mr. I’. H. Stanard, Seattle,
Washington. The following paper is based upon the examina-
tion of these rocks supplemented by brief field notes supplied
by Mr. Stanard. The writer is indebted to Dr. Albert
Johnannsen, United States Geological Survey, for assistance
in the petrographic determinations.
Location.
The Sawtooth Range is a narrow, pinnacled ridge about 15
miles in length, extending in a southwest-northeast direction in
the southeastern part of the Olympics 45 miles due west of
Seattle. Mt. Skokomish, elevation 6500 feet, in Sec. 3, T. 24
N., R. 5 W., and Mt. Henderson, a mile farther northeast, are
the highest points in the range and are located between one-
third and one-half the distance from the southwest to the
northeast end. The southern end of the Sawtooth Range is 6
miles in an air line from Lake Cushman, but by trail is at least
twice as far. Some of the rocks discussed come from near
what is known as Camp Black and Whitet in Sec. 7, T. 24
N., R. 5 W., midway between the crest of the south end of the
range and Box Canyon, through which flows the North Fork
of the Skokomish River. Still others come from Smith’s
* Published with the permission of the Director, U. S. Geological Survey.
+ The following are the most important articles so far published concern-
ing the region: S. C. Gilman, The Olympic Country, Nat. Geog. Mag.,
vol. vii, pp. 133-140, pl. 16, 1896 ; Arthur Dodwell and Theodore F. Rixon,
Forest Conditions in the Olympic Forest Reserve, Washington, Prof. Paper,
U.S. Geol. Survey, No. 7, 100 pages, 20 plates, 1 map, 1902; H.S. Conard,
The Olympic Peninsula, Washington, Science, N.S., vol. xxi, No. 532, March
10, 1905, pp. 392-393; Ralph Arnold, Geological Reconnaissance of the
coast of the Olympic Peninsula, Washington, Bull. Geol. Soc. Amer., vol.
XVii, pp. 401-468, pls. 55-58, Sept. 1906; Chas. E. Weaver, Notes on the
Bedrock Geology of the Olympic Peninsula, The Mountaineer, vol. i, No. 3,
Sept. 1907, pp. 57-64, 1 plate, Seattle, Wash.
¢ It is always interesting to know the derivation of place names, and in
this connection Mr. Stanard furnishes the following note concerning the
origin of ‘‘Camp Black and.White”: ‘‘This camp was named by some of the
early elk hunters from a brand of whiskey of that name, one of the party
being sober enough at one period of their sojourn at this place to mark the
name prominently on u tree.”
10 Lt. Arnold—Locks from the Sawtooth Range.
Camp between 1 and 2 miles southeast of Camp Black and
White, and a few others from the region adjoining the camps.
General Geology.
According to Mr. Stanard, the crest of the southwest end of
the ridge is composed of a coarse conglomerate striking parallel
with the range. The conglomerate has been subjected to
severe crushing and faulting, and quartz veins are not uncom-
mon init. The rest of the country rock consists of alternating
hard sandstone, shale and slate, striking north and south and usu-
ally standing vertical. These rocks have been much fractured
and faulted and intruded by dikes of basic igneous rocks which
locally have produced garnetiferous and other schists. Quartz
veins carrying copper ores in commercial quantities occur along
the contact between some of these igneous dikes and the
intruded sedimentaries. The rocks adjacent to the veins are
also usually more or less mineralized. The age of the rocks is
unknown, but they may be a part of the series of conglomerate,
quartzite, ‘diabase and serpentine that is exposed on the coast
between Cape Flattery and Grays Harbor at the western end
of the Olympies, and which has been described by the writer*
as of supposed pre-Cretaceous age. The occurrence of these
similar series of rocks at both the eastern and western ends of
the Olympics leads to the conclusion that the older formations,
at least, are dominated by east and west strikes, and, therefore,
that the Olympic Mountains, geologically speaking, must be
considered as an east-west range instead of a quaquaversal.
Sedimentary Rocks.
The country rock of the northwestern flank of the Sawtooth
Range consists of hard semi-metamorphosed sandstone and
shale occurring in alternating beds from a few inches to many
feet in thickness. These rocks stand practically vertical and
have in general a north and south or northeast-southwest
strike.
The sandstone, which might properly be called indurated
arkose but hardly a quartzite, is fine-grained and in color dark
gray, and fractures with a rough surface. The rock is trav-
ersed by at least one system of parallel joint planes, in addition
to cleavage parallel to the bedding. Numerous small mica
flakes glisten on the surface in reflected light. In thin slides
the rock is seen to consist very largely of cherty quartz grains,
a little plagioclase feldspar and numerous flakes of brown and
white mica, mostly the latter.
The hardened shale, or slate, as it is more commonly called,
is nearly black, cleaves quite easily and exhibits iridescent
* Bull. Geol. Soc. Amer., vol. xvii, p. 469.
PR. Arnold— Rocks from the Sawtooth Lange. idol
films, probably of manganese oxide, on the cleavage surfaces.
A small fragment of a fossil resembling Dentalium was
noticed in one specimen of slate and indicates the marine
origin of the formation.
Metamorphosed Sedimentary Locks.
The metamorphosed sedimentary rocks consist of garnetit-
erous amphibolite schist, black schist, chert and jasper. They
are confined to narrow zones adjacent to the igneous intru-
sions, and are probably of contact origin.
The garnetiferous amphibolite schist occurs intermittently
near the igneous dikes and is believed to represent a more
advanced stage of metamorphism than the black schists more
commonly associated with the igneous rocks of the region.
The garnetiferous rock is ight greenish to drab in color, shows
the planes of schistosity distinctly and fractures with an
undulating surface parallel with the cleavage and with knife-
like edges in other directions. The specimen examined
contains numerous small pyrite crystals, mostly arranged in
thin layers parallel with the planes of schistosity ; small gar-
nets, though present, are not a common constituent of the
schist. Judging by the general appearance of the specimen,
the metamorphism of the rock was only partially completed.
One wall of some of the mineralized veins of the region
consists of hardened bluish black schist, usually about 10 feet
in thickness, which has been only partially metamorphosed
and which grades to black slate and shale in a direction away
from the igneous contact. This schist is fine-grained, and
exhibits irregular crinkled cleavage faces. It fractures with
sharp edges across the planes of cleavage. In thin sections it
is seen to be composed of lens-shaped aggregations of quartz
surrounded by small parallel stringers of opacite. Mineraliza-
tion with pyrite often takes place in thin bands parallel with
the cleavage, especially near the contact veins.
The only specimens of chert received came from the Black
Trail claim, about 2 miles west of Mt. Skokomish, where it
forms the wall of a quartz vein. It is very hard and fine-
grained, black to dark reddish in color, and fractures along
innumerable joint planes. The chert is usually rich in iron, and
sometimes contains enough lime to render the rock softer than
typical chert. Numerous small quartz veins cut the chert,
usually occupying joint cracks. An impure dark greenish
calcareous shale, approaching chert, occurs in the same locality
as the rock just described. It is seamed with calcite veins
carrying chalcopyrite, which stains the adjacent calcite green.
A light greenish drab i impure limestone mottled with reddish
blotches occurs in layers 2 or 3 feet thick interbedded with
12 Lt. Arnold—Rocks from the Sawtooth Range.
the chert in one wall of the vein on the east flank of Mt.
Henderson. The surface of this rock weathers into minute
pits so characteristic of certain limestones. The red blotches
in the rock are said to sometimes carry small particles of native
copper.
A specimen of material said to occur as float in the region
of Copper Mountain, 6 miles south of Mt. Skokomish, consists
of mineralized red jasper and gray quartz.
Igneous Rocks.
The igneous rocks in the collection embrace typical diabase,
a fine-grained diabase, and a peculiar fibrous serpentine resem-
bling antigorite. The igneous rocks are all younger than the
sedimentaries, occurring as dikes intruding the latter, usually
with a north to northeast trend, parallel with the strike of the
sedimentaries.
The most typical example of diabase occurs as a Tie dike
at Smith’s Camp, and lies adjacent to a dark slate spotted with
aggregations of white quartz. The diabase is moderately fine-
grained, greenish to greenish gray in color, and breaks with a
rough irregular surface. Thin veins of chlorite occur in some
of the joint cracks. Under the microscope, the rock shows
typical ophitic texture. Plagioclase and augite are the most
important minerals, the former predominating. The plagio-
clase occurs in lath-shaped crystals; the augite is slightly pleo-
chroic, and is altered in many cases. Titaniferous magnetite
is found abundantly in isolated grains. Calcite is one of the
alteration products. This diabase is a rock that could properly
be called a greenstone.
Diabase also occurs abundantly, intruding the slates, on the
west side of Box Canyon, where it has been prospected con-
siderably, but with negative results. This rock is fine-grained,
light greenish to oveenish gray and breaks with a rough frac-
ture. Pyrites are plainly visible in small but numerous specks
throughout it. In thin sections, it is seen to be less typically
ophitic in texture than the diabase last described. It contains
about equal quantities of plagioclase and augite, the latter more
pleochroic than in the diabase previously mentioned ; quantities
of titaniferous magnetite and iron pyrites also occur through-
out the mass. Chlorite appears to be the principal product of
alteration.
A specimen of a fine-grained diabase, approaching a basalt in
appearance, occurs as one of the igneous rocks at Camp Black
and White. In hand specimens, it is fine-grained, very dark
colored and breaks with knife-like edges along several irregular
systems of joint planes, parallel with which are sometimes thin
R. Arnold—Locks from the Sawtooth Range. 13
chlorite veins. Fresh surfaces are rough or finely corrugated.
In thin slides, the rock is seen to have fine diabasic texture,
the plagioclase, which oceurs in small lath-shaped rystals,
apparently being more important than the augite, which in
many instances is altered to chlorite. Small chlorite veins
filled with segregations of calcite and calcite masses occur
sparingly throughout the rock. No olivine is seen in the rock
although its general appearance is like many olivine-bearing
basalts.
A specimen ot amygdaloidal basalt, said to have come from
a detached bowlder at Smith’s Camp, exhibits cavities up to
1/16 inch (2"™) in diameter, filled with a soft white mineral,
probably natrolite or a related mineral. This rock has been
erroneously called “bird’s-eye porphyry” by the prospectors.
Serpentine.—A peculiar fine-grained fibrous serpentine,
probably antigorite, occurs in the igneous area at Camp Black
and White. This rock is rather dark grayish green in color and
upon close examination exhibits segregations ‘ofa erayer shade.
It breaks along several systems of shearing planes, producing
a jagged surface. Chlorite associated with a white mineral
occurs abundantly in irregular veins following the fracture
planes. The most interesting feature of the rock disclosed by a
miscroscopic examination is the occurrence in it of numerous
skeleton crystals of olivine now entirely altered to chlorite.
Most of these skeletons appear as long narrow rectangles with
an acute, deep reéntrant angle in each end. There are also a
few better developed olivine crystals mostly altered to calcite.
Radiating bunches of a serpentine-like mineral, probably anti-
gorite, form the groundmass.
Ores.
The ore samples submitted by Mr. Stanard include both
mineralized quartz and slate. A sample which apparently
came from at least 8 or 10 feet below the surface is of slate,
undoubtedly from near the contact with a quartz vein, and
contains chalcopyrite and malachite in moderate amounts.
Another specimen is of gray to dark reddish brown quartz,
containing finely disseminated free copper, and, in the cracks,
thin layers of malachite and azurite ; a black coating, pr obably
a hydrous manganese dioxide like ‘psilomelane or wad, also
occurs prominently in this rock. A third specimen of gr ‘ayish
to reddish drab quartz contains considerable amounts of free
copper with which is associated some red cuprite. These last
two specimens are said to be typical surface specimens. All
of these are from the Three Friends claim, at Camp Black and
White, which, according to Mr. Stanard, shows a eheveraliged
14 LR. Arnold—Rocks from the Sawtooth Range.
zone 650 feet long with an average width of 12 feet. He also
states that ore of this same class occurs on adjacent claims.
Impure gray chert carrying small amounts of chalcopyrite
and malachite, and coated with considerable quantities of
manganese oxide, occur with a decomposed mineralized igne-
ous rock at the Black Trail claim, about 2 miles west of Mt.
Skokomish.
The relation existing between the mineral-bearing and
country rocks in the Sawtooth Range is typically illustrated by
the section at Smith’s camp, which is as follows :
Geologic section at Smith’s Camp, from east to west.
Feet
Diabase 2 3:25 2 pee See ee le 90
Quartz. vein Gee e ee 8
Digibase: 2 os aS en ee - 60
Quantzsv eine ee eee was eee
Semi-metamor phosed black schist, mineralized near
contact with vein: | -. 2 lS). 2 es ee 10
Alternating vertical beds of hard sandstone and shale
or slate wo ie es te er)
Quartz vein (2 a es ee 4
Sandstonesand shales.: 52. 22) 28 ee 20+
One wall of nearly all the veins in the district is igneous
rock while the other may be schist, chert, caleareous chert or
also igneous rock.
From the character of the specimens examined, it seems proba-
ble that the ores in this region consist largely ‘of mineralized
contact vein quartz with which is associated some of the country
rock that has been locally mineralized along contacts with veins
or contacts with intrusive diabase or other basic rocks. The
most valuable ore in those veins which are associated with the
iron-bearing cherts is usually immediately adjacent to the
igneous wall. Next to the igneous wall in some of the veins
is a zone from 4 to 12 inches or more in thickness, filled with
decomposed iron ore; this zone extends for several feet below
the surface and represents a zone of sulphides farther down.
According to Mr. Stanard, the belt of igneous and associated
copper-bearing rocks extends at least as far as Mt. Constance
in Sees. 6 and 7, T. 26 N., R. 8 W., 15 miles northeast of Mt.
Skokomish.
W. M. Bradley—Analysis of the Mineral Neptunite. 15
Arr. IIl.—On the Analysis of the Mineral Neptunite
From San Benito County, California ; by W. M. Brapiey.
Tuer rare mineral neptunite was discovered early in 1907
near the head waters of the San Benito River in San Benito
County, California. It was associated in its occurrence with
the new mineral benitoite, a barium titano-silicate, and at first
was thought to be a new species and received the provisional
name of carlosite.*
A crystallographic and optical study of these neptunite
erystals has recently been published by Prof. W. E. Ford,t
and the present chemical investigation is supplementary to
that article. The mineral has previously been found only in
the Julianehaab district, Greenland, and two analyses of the
mineral were made from material obtained from this locality ;
one by Flinkt, and the other by Sjostrom.§ The results of
their analyses follow:
SiO. TiO. FeO MnO CaO Keo Na,.O MgO
Flink Rebs Lots -10°9 4:97 == 4:88 9°26 0:49 =100°17
Sjostrom Melon ise LO 2d Doo. Orie gl. 953. “= ==100°98
The material used for the present analysis was obtained from
the Brush Collection and was of ideal purity, it being selected
from crystals similar to those used for crystallographic meas-
urements.
Method of Analysis.—A very brief outline of the analytical!
methods employed may here be given. The mineral was
fused with sodium carbonate and silica determined in the
usual way. The filtrate obtained after the removal of the
silica was used for a basic acetate precipitation, and the pre-
cipitate thus obtained eventually fused with acid potassium
sulphate. The titanium was precipitated in a rather strongly
acidified acetic acid solution in the presence of sodium acetate
and SO, water by boiling the solution from three to five min-
utes. In the filtrate from the basic acetate precipitation the
manganese was precipitated as MnO, by bromine water in the
presence of sodium acetate, and after dissolving in strong SO,
water was reprecipitated as ammonium-manganese phosphate.
Calcium and magnesium were determined by the common
gravimetric methods, and the alkalies by making a Smith’s
fusion. Ferrous iron was determined by dissolving the mineral
* Univ. Calif. Pub., v, 9, pp. 149-153, 1907.
+ This Journal, (4), xxvii, 235, 1909.
¢G. For. Forh., xv, 196, 467, 1893; Zeitschr. Kr., xxiii, 346, 1894.
$G. For. Férh., xv, 393, 1893.
16 W. M. Bradley—Analysis of the Mineral Neptunite.
in a mixture of hydrofluoric and sulphuric acids and finally
titrating with KMnO,,.
The ‘analy ses agree essentially with those obtained by the
previous investigators on the Greenland material with the
exception that the percent of MnO present is much smaller
while the amounts of lime and magnesia show a corresponding
increase. The mineral is therefore a silico-titanate of iron
and the alkalies. The results of the analyses are as follows:
I II Average Ratio
DION. see 52°91 52°83 52°87 "875 ~ 4013
SN CO eae era 17°89 17°83 "222 1:017
NNO 2 eee ee "88 "85 ay
OrOues Sonn 1°59 1°53 1°56 027 | B57.
MeO 6 en 1-41 148 144 085 7 =n
Ok Aue eae 11°54 11°83 11°69 162 |
TO HP ae es 5°11 5°06 5:08 054 | :
{0D :
NE OU mare | 9°83 9:98 956 sda ieee ade
100°98 100°78 100°88
The ratios derived from the analysis yield very closely the
following formula—48i0,.1TiO, ARO, i, O, which can be ex-
pressed by the general formula R, RTiSi ,O,, or (Na,K) (Fe, ca
Mg,Mn) Ti Si, O,,.
“This is the same as that given by Flink* as a formula for the
Greenland material.
In conclusion the author here makes known his indebtedness
to Prof. W. E. Ford, who so kindly furnished the material for
this investigation.
Mineralogical Laboratory of the Sheffield Scientific School of Yale Univer-
sity, New Haven, Conn., April 3, 1909.
* Loe. cit.
F. B. Loomis—Turtles from the Upper Harrison Beds. 17
Arr. IV.— Turtles Jrom the Upper Harrison Beds; by
F. B. Loomis.
In spite of the considerable activity in collecting in the
Harrison Beds in the vicinity of Agate, Nebraska, but three
turtles have been described, and these are all from the upper
beds, Two, Testudo edae and T. holland, are known from
nearly complete shells, while 7. avenivaga is based on simply
the pygal and eleventh peripheral plate. During the explora-
tions of the Amherst party in the country between the Muddy
Creek and Agate, Neb., it was their good fortune to find in the
Upper Harrison beds, among other turtle remains, most of the
skeleton of 7. arenivaga and two new Testudine, one of
which is accompanied by an almost complete skeleton.
The entire lack of remains of aquatic forms has always
struck the writer as very suggestive that these beds were
deposited largely, at least, by winds; and of all the groups of
land animals which are most likely to offer aquatic representa-
tives the turtles are most favorable; but, while five species are
now known, and their remains are by no means rare, every
representative is an upland form, and so far all belonging to
the genus Testudo. Among the mammals also the remains are
all terrestrial forms. Then from the structure of the deposits,
the irregular character of the bedding, the presence of occa-
sional large pebbles, and the intermingling of very fine
material with coarser sand, all point in the same direction,
namely wind deposition.
The following paragraphs are descriptive of three turtles ;
of which 7. arenwaga belongs with the large land tortoises
characteristic of the Miocene of western America, while
T. brevisterna and T. undabuna are quite aberrant from the
typical forms of the epoch. The latter two were found on
Muddy Oreek in beds which also contained MMerychyus
minimus Peterson in abundance, and are, therefore, assigned
by the writer to the Upper Harrison horizon.
Testudo arenivaga Hay.
Testudo arenivaga Hay, Ann. Carnegie Mus., IV, 1906, p. 16.
Testudo arenivaga Hay, Fossil Turtles of N. Amer., Carnegie Institute,
1908, p. 430.
The type of this large species is No. 1509 in the Carnegie
Museum, and consists of the pygal and right eleventh peri-
pheral plate, found in the Upper Harrison beds, “two miles
north of Agate Spring Quarry.” Within a mile or two of the
above the Amherst party found a second specimen (No. 2165
Am. Jour Sci.—FourtH Series, Vou. XXVIII, No. 163.—Juxy, 1909.
2
18 F. B. Loomis—Turtles from the Upper Harrison Beds.
of the Amherst Collection) which includes the portion found
by the Carnegie party, together with the front of the plastron,
the skull, shoulder girdle, humerus, pelvis, femur, a large
number of dermal ossicles and fragments of other bones.
Three species of giant land tortoises have been described,
all agreeing in a general way and being distinguished by hay-
ing a der mal armature of small bones, in addition to the shell.
These are Testudo osborniana from the Pawnee Oreek beds,
T. impensa from the Loup Fork of Montana, and 7. orthopygia
from the Upper Miocene of Kansas. To this group 7. areni-
vagw belongs, making four representatives from the middle
West.
The skull of 7. arentvaga is relatively the widest of any of the
known forms in this group (and all of the four are known by
practically the whole skeleton), triangular in form, with rather’
Fie. 1.
Fie. 1. Testudo arenivaga, the skull from the palatal aspect. 1%
nat. size.
Fic. la. Lower jaw from the side. 1 nat. size.
heavy bones, and with the lateral angies extending shghtly
behind the occipital condyle. It is also relatively low.
Measurements.
Length, snout to occipital) condyles s2 252°) 222352. Liao
Width across the quadrates/. 22.20... .. 23.2.2. 22 2) See
Heicht at back of maxilla2:22 222 22. ...- 152-2.)
The top of the frontal is somewhat crushed, but the margins
remain and show the interorbital region to be moderately wide
F. B. Loomis—Turtles from the Upper Harrison Beds. 19
(32™"). The jugal arch is unusually heavy, being 19"™ wide
at the narrowest part. The palate is high vaulted and rather
narrow. The masticatory surfaces of the maxille are wide,
and have three ridges, and two longitudinal grooves. The imar-
ginal ridge is high and sharp, slightly dentate and overlaps the
mandible extensively. The median ridge is low but acute,
while the innermost one is rounded and crossed by shallow
strie. The two inner ridges do not continue onto the pre-
maxille, which have a deep depression, into which evidently
fitted a strong horny tooth on the lower jaw. The posterior
nares open far enough back so that they are behind the shelf
just described. On either ptery-
Fic. 2. goid there is a shghtly hooked
ectopterygoid process.
The lower jaws are rather nar-
row, 26" high at the coronoid,
and the upper margin contains
a deep groove, bounded by two
sharp edges, of which the inner
is the higher.
Of the carapace but a small
portion of the rear was pre-
served, but that fortunately
included the half of the pygal,
suprapygal and the eleventh
peripheral, which correspond
almost exactly in dimensions and
thickness with those of the type,
so that the association may be
considered unquestionable, imas-
; much as the two came from
‘within a mile or two of each
other.
Of the plastron the anterior
lobe of the left side and some
’ fragments were found. The
Fic. 2. The anterior portion of whole lobe is about 330" wide
the piastron of T-arenivaga. “4 and 240™ long, indicating that
the shell was relatively long
and narrow. The lip is prominent, being 148" wide at the
base and 75"™ long on the median line. The anterior corners
are rounded and there is a small notch in front, making a form
in itself distinctive. From the front, the lip thickens rapidly
until, when 115™™ back, it is 75™" thick. It then drops down
abruptly, the escarpment being strongly excavated behind.
The following measurements of plastral scutes are all that can
be given: On the median line, the gulars occupy 125™",
hamerals 105™", and the pectorals but 15™™.
‘
tat ’ Peete Aces
Poe AACA LLALAD 232 LW Hest they Dita OP EES
ea 8
wheter
wed
Ey naar tLe
20 FB. Loomis—Turtles from the Upper Harrison Beds.
The shoulder girdle is practically complete. The scapula is
a flattened bone about 145™™ long and, near the glenoid end,
is about twice as broad as it is thick. It makes an angle of
120° with the procoracoid process, which is 95™" long. The
coracoid is a broad triangular bone, measuring 85™™ along the
medial side, 75™™ along its front border and 105™™ along the
posterior border. The humerus is a heavy bone, 173™™ long,
with a head 45™™ in diameter. However, for the size of the
HiGaio: Fie. 4.
—_—_—_———.
Fic. 3. Humerus of T. arenivaga from the radial size. 1% nat. size.
Fic. 4. Femur of T. arenivaga. 16 nat. side.
skull, this, as is also the case with the other limb bones, is
relatively light when compared with that of 7. orthopygia,
T. osborniana, or T. pensa. The lesser tubercle is swung
well to the rear; so the intertubercular suleus between it and
the wing-like greater tubercle is unusually narrow and deep.
The pelvis is also relatively light and offers no particular
features. The femur is relatively small, being 142™™ long,
the shaft being much flattened toward the distal end. At the
condyles it is 56™" wide. A few phalanges are present, the
F. B. Loomis—Turtles from the Upper Harrison Beds. 21
end ones being about 25"™ long ; and the next to the last only
about 15™™.
On the under sides of the feet and along the forelimb up to
the elbow, and presumably under the tail, numerous denticles
occur. Along one fore limb over 50 were found. As Hay
has suggested, these helped to close the openings at the front
and rear of the shell. They are characteristic of these large
forms; and, judging from the fact that in every species the
skeleton has been preserved, they may well have been most
effective in completing the armature. They may be used to
bind together into a subordinate group such Testudine as
possess them.
Testudo brevisterna sp. nov.
The type of this species is No. 2006 in the Amherst Collec-
tion and was found in the Upper Harrison beds, on Muddy
Creek in the north edge of Laramie Co., Wyoming. The type
includes the carapace, plastron, skull, shoulder girdle, fore
limb (except foot), pelvis and the hind limb (except foot).
The skeletal portions were found within the shell and indicate
that the turtle died while withdrawn. It apparently lay some
time before being buried, as the bones are in many eases eaten
into, either by animals or decay. This specimen was found in
close proximity to the skeleton of Merychyus minimus, which
marks the beds on Muddy Creek as Upper Harrison.’
The turtles nearest in the arrangement of their plates to
Testudo brevisterna are T. vaga from the Pawnee Oreek beds
and 7. edae from the Upper Harrison, both of these agreeing
in having only neurals 1 and 3 tetragonal, while the second is
octagonal: but in 7. brevisterna the fourth neural is hex-
agonal, while in both the other forms it is octagonal. 7. edae
is further isolated by having only seven neurals. The species
T. brevisterna is peculiar in the abrupt way the carapace falls
off behind, the rear portion of the shell being almost vertical,
and its middle portion extending below the plastron, thus
practically closing the rear of the shell.
The skull of this specimen is nearly complete, only the left
quadrate region and the basioccipital being lost. In this skull
there are such marked peculiarities that, among the few
Testudinz of this type, the writer finds no other species with
which to compare it. The skull is wide and short, being as
wide across the quadrate region as it is long from the snout to
the occipital condyle. It is very low and the arcades are
heavy. The large prefrontals (18™™ along the median line)
almost exclude the frontals from bordering on the orbit. The
small frontals (12™™ long) are much reduced, the larger parie-
tals overshadowing them. The vault of the palate is very low
22 FB. Loomis—Turtles from the Upper Harrison Beds.
and has a median ridge running from the basisphenoid onto
the premaxille. The 1 masticatory surface has three ridges and
two longitudinal furrows. The low, sharp outer ridge bounds
the jaw, overlapping the lower jaw but little. The middle
and inner ridges are still lower and rather obtuse. The median
ridge mentioned above as continuing onto the premaxille
separates two deep pits, one on either side, which evidently
Hie. 9.
Fie. 5. Skull of T. brevisterna from above. 1 nat. size.
Fic. 5a. The quadrate and otic region seen from the side to show the
narrow ear opening and the forward projection of the quadrate. 1g nat.
size.
received two horny teeth on the front of the lower Jaw. There
is a strong ectopterygoid process on either pterygoid bone.
The opening for the ear is greatly narrowed, ne a very
characteristic feature. (See fig. 5a.)
Measurements.
Length from the snout to the supra occipital crest ___- -- -- sor
Length from the snout to the occipital condyle (estimate).. 70™™
Widthsacross the quadrates) 2 25220525 5)". ee DO
Width.of interorbital région? 2.25 42) 2 i ee
Leneth of ear opening). 22 5.2 elif. 2s
Height of ear opening... 22.2025 -22 2.21. 1 2
The short, widespread lower jaws have a longitudinal
groove bounded by sharp ridges of nearly equal height. The
jaw is 55™™ long and 19™™ high at the coronoid.
The carapace is only 386°" long and nearly as wide
(360™"), being high arched (148"™ high). The greatest width
is near the front and it narrows slightly as it approaches the
rear. The back of the shell drops off very abruptly, being
almost vertical, and extending below the plastron near the
middle line. The dimensions of the various plates appear in
the table below:
F. B. Loomis— Turtles Srom the Upper Harrison Beds. 28
Neurats Vertebrals
Length Width Length Width
1 63 40 1 Le 125
2 40 46 2 85 98
3 38 49 3 90 100
4 36 52 4 68 80
dD 34 48 5 104 155
6 29 45
7 28 45
8 38 36
Fic. 6.
Fic. 6a. The carapace of T. brevisterna, projected on a flat surface.
The posterior part is a little spread. 14 nat. size.
Fie. 66. Plastron of same.
This individual seems to be very old and the sulci marking
the outline of the scutes are but dimly marked. There is a
low boss on the first neural. Both neural 1 and 3 are tetra-
gonal, 3 is octagonal and the others are hexagonal. The upper
suprapygal is as usual in the genus. Costals 2, 4, 6, and 8 are
narrow above, but spread distally, having a wide base below.
Costals 1, 3, 5,.and 7, on the other hand, are wide above and
narrow below.
24 F. B. Loomis—Turtles from the Upper Harrison Beds.
The plastron is 429"™ long and 220™™ wide, the anterior lip
projecting far in front of the carapace. The tront of the plas-
tron is turned upward, the lip projecting straightforward from
it. The rounded anterior end of the lip is deeply notched, and
from the front it thickens until about 70™™ back the lip is
about 30™" thick. Just behind this point it drops down, mak-
ing a considerable wall. The endoplastron is 70™ long and
ime 9 Fie. 8.
Fic. 7. Humerus of T. brevisterna from the radial side. 14 nat. size.
Fig. 8. Femur of T. brevisterna. 4 nat. size.
86™" wide. The relationships of the different elements are
shown in the scale drawing, fig. 6.
The scapula is a flattened bone (92™ long) making an angle
of 119° with the procoracoid (62™™ long). The humerus is
greatly flattened and very broad, the lesser and greater tuber-
cules being wide spread, and having a broad intertubercular
suleus between them. The head of the humerus, however, is
relatively small (see fig. 7), but the distal end of the bone
is again wide and flat.
The pelvis has a short stout ilium, and the whole build of
pubis and ischium is heavy, especially the short prepubic process.
The femur, unlike the humerus, is a short, stout bone, 82™™
long and widely oval in section. Both the tibia (65™™ long)
and the fibula (70™ long) are rod-like with a cireular cross
section, and taper gradually toward the distal end. The feet
are wanting.
While the cervical and caudal vertebre are present they
fF. B. Loomis—Turtles from the Upper Harrison Beds. 25
offer no specific characters, unless it is that the tail was short
and weak.
Testudo undabuna sp. nov.
The type of this species (No. 2007 in the Amherst collec-
tion) is a carapace, lacking the pygal and eleventh peripherals,
and the median portion of the plastron, the shell belonging to
a very primitive type of Testudo. It was found in the Upper
Harrison beds on Muddy Oreek, Laramie County, Wyoming.
The species is peculiar in having the suture between the
first and second costal plates start from the first neural plate,
Fic. 9. Carapace of Testudo undabuna as projected on a flat surface. 1¢
nat. size.
making it hexagonal, a condition paralleled among American
fossil turtles only in Zestudo laticuneata from the Oligocene.
No neural plates are octagonal and only the third is tetragonal.
The surface of the carapace is covered by undulatory lines
which follow the outlines of the epidermal scutes.
The carapace of the type is 205" long and 155™™ wide, the
outline of the shell being regularly ovate with a slight notch
in front, and unusually low vaulted for a land tortoise. The
dimensions of the neurals are given in the table below.
26 FL. B. Loomis—Turtles from the Upper Harrison Beds.
Neurals Vertebrals
Length Width Length Width
i! 30 22. i 46 ‘57
2 My 30 2, 37 47
3 20 22 3 386 o2
4 Le. 20 4 46 52
5 18 28 5 50 82
6 12 28
t 12 24
8 9 18
The second, fourth, sixth and eighth costals are narrow
above and wider below; the first, third, fifth, and seventh are
wide above and narrow below.
As only the central portion of the plastron is preserved, but
few characters can be gleaned from it. The species seems to
be at least fairly common, both in the beds along the Muddy
Creek and also along Raw Hide Creek, no less than five
specimens having been found.
Amherst, Mass.
B.S. Butler—Pyrogenetic Epidote. 27
Art. V.—Pyrogenetic Epidote ;* by B. 8. Burrer.
AN occurrence of epidote as an apparently original constitu-
ent of a dike rock was observed by the writer in 1907, while
engaged in field work in the Shasta County copper region,
California. This recalled the question as to whether or not
epidote is ever a pyrogenetic mineral. In the occurrence to
be described, the evidence of primary origin seems unusually
good, and, although the material obtained is not as fresh as
could be desired, since all the specimens were collected from
surface outcrops, yet it is thought worthy of presentation.
In order that the evidence may be properly weighed, it may
be well to preface it with a brief review of some of the occur-
rences described by previous observers.
One of the best known of these in the United States is that
of allanite and epidote in the granites of Ilchester, Maryland,
described by Professor W. H. Hobbs.t Concerning the origin
of the minerals Professor Hobbs says: “‘ With little doubt the
latter (allanite) is one of the earliest separations from the
magma. ‘The origin of the epidote is not so easily settled, but
the ‘stretched’ character of the granite is in favor of a meta-
morphic origin, through pressure. Against such a view is the
discovery by Professor Williams that the Woodstock granite,
which is particularly rich in these intergrowths, shows no evi-
dence of cataclastic action.” In a later publication the author
expresses the belief that the epidote of the [chester granites,
in some cases at least, is an original mineral. The Maryland
granites were later studied by Mr. C. R. Keyes,§ who concludes
that both the allanite and epidote are of primary origin. A.
Lacroix| describes intergrowths of epidote and allanite closely
resembling those of [chester, in which the epidote is con-
sidered as an original mineral. Professor W. C. Brégger™]
describes similar intergrowths and considers the epidote, in
some cases at least, to be of pseudomorphic origin. Professor
Frank D. Adams** describes the occurrence of epidote and
allanite in granites from Wrangell Island, Alaska, and Pelly
River, Yukon district, Alaska. In both cases the epidote is
considered as a mineral which has grown in the rock after its
consolidation, but without recrystallization of the other con-
stituents.
* Published by permission of the Director of the U. S. Geological Survey.
+ This Journal (8), vol. xxxviii, pp. 223-228.
¢ Am. Geol., vol. xii, p. 218, 1898.
$ Geol. Soc. Am. Bull., vol. iv. pp. 305-312.
| Bull. de la Soc. Frangaise de Minéralogie, vol. xii, Apr. 1889.
*| Zeitschrift fiir Krystallographie, xvi, p. 99, 1890.
** Canadian Record of Science, 1891, p. 344.
28 B.S. Butler— Pyrogenetic Epidote.
Mr. W. H. Turner* considers epidote occurring in a fresh
soda-granite from California as probably original. Messrs.
Alfred E. Barlow and W. F. Ferrier,t describing epidote
occurring in Laurentian gneisses, consider it as primary, and
in a classification of the rocks, the micaceous gneisses are sub-
divided on the basis of primary and secondary epidote. These
are described by the authors as follows:
“‘ Biotite-epidote-gneiss. The combination of biotite and epi-
dote as the principal colored constituents forms a well-defined
rock-type which has been found to be remarkably constant over
large and widely separated areas ..... The rocks are un-
doubtedly of irruptive origin, and are, in fact, foliated granitites,
thoroughly holocrystalline and granitoid, varying from coarsely
to finely crystalline.”
Under the description of the epidote they make the follow-
ing statements:
“Next to the biotite, this is by far the most abundant of the
coloured constituents of the granitic gneisses and it also enters
largely into the composition of the more basic hornblendic ones.
In addition to the ordinary occurrence of the epidote as an altera-
tion product, we have also the strongest evidence that it exists in
a large number of cases as an original and important constituent
of the rock mass.
The manner in which the perfectly fresh crystals, possessing
sharply defined outlines, occur inclosed by wholly unaltered bio-
tite in rocks which have been subjected to only a slight degree of
pressure, admits of no reasonable doubt as to their primary
Ma PUG 5s etar. The crystals occasionally contain cores of a pleo-
chroic brownish substance which is probably allanite, but no
thoroughly typical examples of that mineral were detected.”
As seen from the foregoing descriptions, in most of the
occurrences where epidote has been considered primary it has
been associated with allanite, the two exceptions being the
occurrence noted by Mr. Turner, where allanite is not men-
tioned as a constituent of the soda-granite, and that of Messrs.
Barlow and Ferrier, in which allanite is only rarely associated
with the epidote.
The evidence of pyrogenetic origin adduced in these cases
has apparently not been entirely convincing. Several of the
recent text-books on petrography question the occurrence of
epidote as an original constituent of igneous rocks. Mr.
Waldemar Lindgren,t in a recent paper: “‘ Relation of ore
deposits to physical conditions,’ does not include epidote
* Jour. Geol., vol. vii, p. 155.
+ Canadian Geol. Survey, vol. x, pp. 70-87, 1907.
t{ Econ. Geol., vol. ii, p. 105, 1907.
B.S. Butler—Pyrogenetic Epidote. 29
among the pyrogenetic minerals, and Mr. William H. Emmons,*
in a later article: “ A genetic classification of minerals,” ques-
tions its occurrence as an original constituent of igneous rocks.
The epidote in Shasta County, California, occurs as an
accessory mineral in small dikes cutting an extensive mass of
soda-granite porphyry. This main intrusive is the enclosing
rock of the copper deposits west of the Sacramento River. It
is roughly elliptical in outline with major diameter exceeding
10 miles and the minor diameter 3 to 4 miles. Near the cen-
ter of this intrusive mass, in the vicinity of the Balaklava,
Shasta King, and Spread Eagle mines, are several small dikes
which appear, from field relation and chemical composition, to
be the result of differentiation from the main intrusive rock.
It is in these dikes that epidote is found with the characteris-
ties of an original mineral.
Both the large intrusive mass and the dikes are of unusual
composition, being characterized by very low content of potas-
sium and calcium with high soda.
_ Analyses of the soda-granite porphyry and one of the dikes
by Mr. George Stieger, of the U. S. Geological Survey, give
the following composition :
I II
SOS peat 80-09 ty 268-15
PURO eee ee 10°80 16°75
Res oe 1:07 48
eG ees tt 83 17D)
MICO eee ee 58 83
CO ae eke 38 89
INA OR EE 5ag0 6°95
KG Oe Bee er none 80
HIO ee ee "24 84
Pi Oepscr nt 52 1:52
a0 Fee cee ae pe eles 16 DH
ZrO, a ge ee "01 none
ONS Nes Ce eee none none
AO Gary ea 262i 04 16
es none none
Shin oes eee eee oe Ne none none
VEO ee nO 04
|) Se COI eee ie none 03
Si ho RSS eae none 03
160°34 100°06
I. Soda-granite porphyry near Shasta King mine.
If. Porphyry dike near mouth of north tunnel of Spread Eagle
mine.
* Econ. Geol., vol. iii, p. 611, 1908.
30 B.S. Butler—Pyrogenetic Kpidote.
These dikes, which occur scattered over several square miles
in this locality, differ somewhat in appearance, chiefly due to
difference in weathering, but are very uniform in mineral
composition. The freshest specimen obtained was from the
dike at the Spread Eagle tunnel. This is a greenish-gray
porphyritic rock containing phenocrysts of quartz, plagioclase,
altered biotite and epidote. The quartz crystals are (not :
abundant and show marked corrosion. The plagioclase pheno-
erysts are very striking, being almost pure white in color and
nearly euhedral in form, the latger reaching 8™ in length.
Biotite crystals are rather scattering and show strong chloriti-
zation. The epidote occurs in well-formed crystals scattered
sparingly through the rock. The largest observed was 12™™
in length, though most of the crystals do not exceed 5™™ in
greatest dimension. They are of sufficient size and abundance
to attract the attention at once and were found in every dike
of this character examined.
Under the microscope the quartz phenocrysts show pro-
nounced corrosion, having entirely lost their crystal outline.
The feldspar crystals in many cases are twinned according to
both the albite and periclne laws. Extinction on 010 varies
from +7 to +10, with index slightly lower than Canada
balsam. These properties correspond to an oligoclase with a
composition about Ab,An,. The crystals are clouded with
minute dark specks and in some instances there has been con-
siderable kaolinization. The biotite has suffered extreme
alteration, in some cases to a green pleochroic mica with the
separation of iron ore; in other cases alteration has produced
chlorite, epidote and iron ore. In a few instances serpentine
has resulted from the alteration. A few crystals of unaltered
muscovite or paragonite are present in the specimens.
The groundmass is composed of unstriated feldspar, with
small amounts showing twinning, also of quartz and altered
mica. The analyses indicate that the feldspar of the ground-
mass 1s lower in lime than the phenocrysts. Accessory min-
erals are epidote, apatite, zircon, and titanite. Many of the
epidote individuals evidently once possessed a definite crystal
outline, though in most cases there has been enough corro-
sion by magma to destroy the sharp erystal faces. In some
instances this corrosion has produced embayments in the crys-
tals. The contact between the epidote and the groundmass is
pertectly definite, there being no fingering out of the epidote
into the enclosing ; gvroundmass. <A few erystals of quartz and
apatite are included in the epidote. The included quartz
crystals show nearly perfect crystal outline, and have escaped
the corrosive action of the magma, which has affected the.
epidote and the quartz not thus protected. The evidence
B.S. Butler— Pyrogenetic Epidote. 31
indicates that the quartz and epidote were among the earliest
minerals to crystallize; both were earlier than the feldspar
and biotite, at any rate the latter minerals do not show the
corrosive effects that characterize the former.
The epidote possesses the optical properties characteristic of
that mineral. Pleochroism a pale greenish-yellow, 6 pale
lemon-yellow, c nearly colorless. Absor ption CSb>a. Twin-
ning plane 100. Cleavage 001 and 100 distinct. Plane of
optic axes 010. anc=2° 25’ average of several readings.
Angle between 100 and 001 = 114° 26/ average of measure-
ment on several crystals. Optical character(—). y—a@= ‘024,
determined by table of birefringences.
A separation of the epidote was made by breaking the
erystals from the matrix. In this manner material that was
fully 50 per cent epidote was obtained. This was crushed to
pass a 100-mesh sieve and the powder separated by Thoulet’s
solution at maximum density. The material obtained was
examined microscopically and found to be practically pure
epidote. An analysis of this material by Mr. W. T. Schaller,
of the U.S. Geological Survey, gave the following composition :
Analysis of Epidote from Shasta Co., Cal.
Sratimeyen ein 60 hae ee 38°22
wid gis Sencar Seine 0°33
EO p19
LoL) Se Ae ES ae) See te ge semen 8°75
Re Oe SON NP ah 1°25
iO Reta S802 SY LS PE oe On SUE 0°19
RO eee Aas fo SU dad trace
eierer Aare eh sor, Set 22°77
HE ONG ae Sore tan ated A Was a 06
JS ALO pete oe ge b pene bP er eeeee a Mee 11
AG ak eee ee ere 52
TAG teSS Se ik eet -eapel dee en tee a 3°04
100°36
aes Caethisns ei Ji. oil ees 324° “none
Density (approximately) . peed Ne 3°29
It is seen that, disregarding the minor constituents, the
mineral conforms very closely to the formula (Ca,Fe), (AlOH)
(Al, Fe), (Si0,),, the molecular ratio of calcium to ferrous
iron being CaO: FeO:: 24:1, and that of aluminium to ferric
iron Al,O. ree Oso £5 +E
Aside fron the fs egoing evidence of the primary origin of
the epidote there are additional reasons for believing that it is
not secondary. The large crystals of epidote appear with
32 B.S. Butler—Pyrogenetic Epidote.
equal abundance in various stages of alteration of the differ-
ent dikes. Where secondary epidote develops in the altera-
tion of biotite and feldspar, it is in minute grains and shows
no tendency to collect in large crystals. The very low lime
content of the rock would permit of the formation of but a
small amount of epidote, and it is difficult to conceive of con-
ditions of alteration that would cause all this to collect in a
few large crystals, if it had been originally disseminated
through | the rock. Inthe freshest dikes the feldspars show
but slight alteration, and could not have furnished sufficient
CaO from this alteration to form the epidote. The enclosing
rock is extremely low in lime, and cannot be looked upon as.
a source of this material for the formation of the epidote.
The dikes are near the center of a large intrusive mass and
therefore are probably not affected by formations surrounding
this large mass.
Considering the dikes as the result of differentiation of the
magma represented by the main intrusive mass, it is seen that
there has been a decrease in SiO, with increase in most of the
remaining oxides ; the relative increase in lime is much greater
than in soda. From this it would naturally be expected that
the feldspar of the dikes would be distinctly more basic than
that of the main intrusive. The feldspar of the groundmass
in both rocks is too small for accurate determination, but so
far as can be judged by the phenocrysts, there is little differ-
ence in the composition of the feldspars in the main intrusive
and in the dikes. Assuming that the feldspars in the two
rocks are of the same composition, the excess of lime m the
dike rock may be considered as available for the formation of
epidote.
In calculating the composition of the dike rock we may
assign enough CaO to combine with available P,O, to form
apatite, an amount equal to the total CaO present in the main
intrusive to form anorthite, and there is still remaining suffi-
cient to form 1:41 per cent of epidote of the composition
shown by the analysis. As the amount of feldspar in the
dikes is greater than that in the enclosing rock, it wonld
require slightly more CaO than is present in the main intru-
sive to form feldspar of the same composition. This would
reduce the amount of epidote slightly, but it would probably
still be above one per cent. It is dificult to estimate the per-
centage of epidote present in the scattered crystals, but it
certainly seems to correspond well with the amount roughly
calculated above.
Washington, D. C.
Gooch and Perkins—Determination of Free Iodine. 33
Arr. VI.—The Gravimetric Determination of Free Lodine
by the Action of Metallic Silver; by F. A. Goocu and
CLAUDE C. Pans
[Contributions from the Kent Chemical Laboratory of Yale University—ce. ]
Waen in analytical operations it becomes desirable to deter-
mine free iodine in the presence of iodine combined in an
iodide, it is usual to have recourse to volumetric procedure
involving the preparation of standard sodium thiosulphate, for
use in neutral or acid solution, or of standard arsenite, for use
in solutions made alkaline by a bicarbonate.
inress Ie
The present paper is an account of an endeavor to utilize
the well-known affinity between silver and iodine as the basis
of a gravimetric method for the determination of iodine in
general, and, incidentally, for the gravimetric standardization
of iodine solutions to be used in volumetric analysis.
Inasmuch as the facility with which combinations may
take place between substances varies with their physical con-
ditions, several preparations of silver were tried with a view
to finding the form of silver best adapted to the purpose of
taking up iodine in analysis. The iodine was used in N/10
solution prepared in the usual way (12°7 gms. of iodine to 18
gms. of potassium iodide in one liter) and standardized against
arsenious acid.
Am. Jour. Sci.—FourtuH Series, Vou. XXVIII, No. 163.—Jury, 1909.
3
34. Gooch and Perkins—Determination of Free Iodine.
The procedure was simple. The standard N/10 iodine solu-
tion was drawn from a burette into a 250° Erlenmeyer flask
containing a weighed amount of finely divided silver. The
flask, properly trapped and attached to a mechanical shaker
adjusted to give the liquid a rapid rotary motion, was shaken
until the iodine color had vanished. The liquid, usually 50°%™* in
volume, was diluted to about 100°™* and the residue of silver
and silver iodide, collected in a perforated crucible fitted with
asbestos felt, was washed, dried at 130° to 140°, and weighed.
The difference between the weight of silver taken and that of
the residue of silver and silver iodide should, according to the
theory of action, be the measure of the free iodine. The
accompanying cut shows the mechanical shaker and the adjust-
ment of apparatus used throughout the work. The flask at
one side, fitted with a bulb-trap held in place by an outer
rubber band, was used in the experiments of Tables I and II.
The flask mounted upon the shaker was used for the operations
carried out in hydrogen and recorded in Tables III and LY.
In Table I are given the results of experiments made with
silver reduced in the wet way, by the action of zine upon silver
chloride (A), silver nitrate (Bb), or silver iodide (C); and, m a
dry way, by the action of hydrogen upon silver sulphide (D),
or upon silver oxide (EK). In the first set of experiments of each
sort the reduced silver was dried and used without special
previous treatment; in the second set of each sort the reduced
silver was shaken with a solution of potassium iodide, washed,
and dried before being used to absorb the iodine. The object
of shaking the reduced silver with potassium iodide was to con-
vert to silver iodide any incompletely reduced silver chloride,
nitrate, or sulphide, and this treatment does reduce considerably
the very large error noted in all of the experiments with the
untreated silver; but the similar, if less marked, effect upon
silver reduced from the iodide suggested that a part of the
unfavorable effects in the case of the untreated silver might
be due to action between potassium iodide and metallic com-
ponents of the zinc. Even in those experiments in which the
reduced silver was previously treated with potassium iodide ~
the errors are too large and too variable for a good analytical
process.
Gooch and Perkins—Determination of Free Iodine.
Sys)
Taste: I.
The Action of Silver Reduced by Chemical Processes.
-Silver
taken
erm.
bo
~I
ww www
jen)
co)
bo
Ww ww Ww CO w
Increase
Iodine in weight Error in
taken of silver iodine Remarks
erm. erm. erm.
A)
The action of silver reduced from AgCl by zinc.
0°6473 0°6833 + 0°0360 The silver
0°6473 0°6861 + 0°0388 was used
0°6473 0°6877 +0:0404 without
0°6473 0°6830 +0°0357 previous
0°6473 0°6829 +0°0356 treatment
0°6461 0°6475 +0°0014 The silver was
0°6461 0°6483 +0°0022 previously
0°6461 0°6494 + 0:0033 treated with KI
The action of silver reduced from AgNO; by zine.
The silver was used
0°6461 0°6677 +0°0216 Souk :
0°6461 0°6656 Leone hue eee
treatment
0°6461 0°6464 +0:°0003 The silver was
0°6461 0°6472 +0°0011 previously treated
0°6461 0°6470 + 0°0009 with KI
(C)
The action of silver reduced from Agl by zine.
0°6461 0°6513 +0°0052 The silver
0°6461 0°6519 +0°6058 was used
0°6461 0°6514 +0:°00538 without
0°3217 0°3257 +0°0040 previous
023217 0°3261 +0°0044 treatment
0°6434 0°6444 +0:0010 Lae ae wee
0°3917 0-3931 40-0014 Previously treated
with KI
(D)
The action of silver reduced from Ag2S by hydrogen.
0°6473 0°6574 +0:0101 Silver used without
(°6473 0°6577 +0:0104 previous treatment
0°6461 0°6473 +0°0012 The
0°6461 0°6472 +0°0011 silver was
0°6461 0°6475 +0°0014 previously
0°6461 0°6483 +0°0022 treated
0°6461 0°6525 + 0°0064* with KI
(E)
The action of silver reduced from Ag,O by hydrogen.
0°3217 0°3250 +0:0033 Silver used without
previous treatment
* Stood for several hours in the solution,
36 Gooch and Perkins—Determination of Free Iodine.
The experiments next described were made with silver
deposited electrolytically from a solution of silver nitrate upon
a platinum cathode, the anode being enclosed within a porous
cell to prevent admixture of the silver dioxide formed at the
anode with the metallic silver at the cathode. Experience
showed that, while the bright and erystalline deposit which
formed upon a stationary cathode lacked in absorptive power,
the product obtained by continually oscillating the cathode
during the deposition of the metal, broken and dark when
formed, proved to be sensitive to iodine as well as pure. . The
results of experiments with electrolytic silver thus prepared
are given in Table II.
Tape I.
The Action of Llectrolytic Silver.
Increase in
Silver Iodine weight of Error in
taken taken silver iodine
grm. grm. germ. erm.
2°8184 0°6461 0°6494 +0°0038
BD 1BO 06461 0°6490 + 0°0029
2°0514 0°6461 0°6491 +0:0080
3°0102 0°6461 0°6490 +0:0029
75943 (cryst) 0°6479 0°6513 +0°0034
Though the silver used in this process was pure, the errors
observed are positive and high; and this fact emphasizes an
obvious inference from the previous work that the excess in
weight is due to the absorption by the silver of an extra amount
of iodine liberated from the potassium iodide by prolonged
agitation in contact with the air. In harmony:with this idea
is the fact, observed throughout the entire series of experiments
with silver reduced by chemical processes and subsequently
treated with potassium iodide, that the error is greatest when
the time used to accomplish the absorption is the longest.
This was especially marked in the experiments with silver
reduced by hydrogen, in which the largest amount of time was
needed, on account of the less sensitive character of the glisten-
ing and filamentary metal.
‘Moreover, direct experiments in santeln the silver was shaken
with 50™* of a solution of potassium iodide, 208" to the liter,
fully confirmed the idea that the action of air must be pr evented
during the agitation of the solution of the iodide in contact
with silver ; for in these experiments it was found, that from
the solution of potassium iodide shaken in contact with air
finally divided electrolytic silver absorbed 0-0010®™ of iodine
in fifteen minutes, that silver reduced by zine from silver
iodide absorbed 0:00128™ of iodine in fifteen minutes, that
silver reduced from the sulphide by hydrogen took up 0-00826™
Gooch and Perkins—Determination of Free Iodine. 37
of iodine in one hour, and that crystalline electrolytic sil-
ver took up 0:00518™™ in one hour and forty-five minutes.
This action of air once shown, the next step was to investigate
the behavior of silver in contact with potassium iodide pro-
tected from the action of the air. Im Table III are recorded
Tasxe III.
The Action of Silver upon N/10 Iodine in an Atmosphere of
Hydrogen.
Inerease in Average
Silver Iodine weight of Error in error in
taken taken iodine iodine iodine
erm. erm. erm. erm. erm.
(A
The action of silver reduced from ‘AgCl by zine and treated with KI.
3°0000 0'6461 0°6464 + 0°0008
1:0000 0°6447 0°6448 + 0°0001 + 0°0002
(B)
The action of silver reduced from AglI by zine and treated with KI.
3°6293 0°3217 0°3221 + 0°0004
3°2049 0°3217 0°3225 +0°0008
3°0000 0°3217 0°3219 + 0°0002
3°0068 0°3217 0°3212 —0°0005
3°0049 0°3217 0°3221 + 0°0004
3°0026 0°6434 06441 + 0°0007
2°9990 0°3217 0°3214 — 0°0003
3°0005 03217 0°3214 — 0°0003 +0:°0002
The action of
(C)
silver reduced from Ag.S by hydrogen and treated with KI.
3°0000 0°6461 0°64638 + 0°0002
3°0000 0°6461 0°6460 —0:0001 +0:0001
(D)
The action of silver reduced from Ag.,O by hydrogen.
3°0000 0°6434 06443 + 0°0009
3°0000 0°6434 0°6430 —0'0004 +0:00085
The action of silver reduced electrolytically from AgNOs.
4°4189 0°6447 0°6447 +0:°0000
3°0025 0°6447 0°6448 +0°0001
3°0009 0°6447 0°6443 — (0004
3°0157 0°6447 0°6445 —0°9002
3°0000 0°6447 0°6444 —0°0003
3°0000 0°6447 0°6452 + 0°0005
3°0004 0°6447 0°6443 —0°0004
3°0043 06447 0°6443 —(0°0004
3°0000 0°6434 0°6430 —0°0004
3°5810 0°3217 0°3221 +0°0004
3°0000 0°3217 0°3219 + 0:°0002 —0°0001
38 Gooch and Perkins—Determination of Free Todine.
the details of experiments in which the standard N/10 solution
of iodine in potassium iodide was shaken N/10 silver in flask
filled with hydrogen and closed.
These results make it plain that free iodine may be deter-
mined with accuracy in the presence of potassium iodide b
shaking the solution with metallic silver in a closed flask filled
with hydrogen and determining the increase in weight of the ~
silver. Silver reduced from a silver salt by zinc or from silver
sulphide by hydrogen may serve the purpose, provided it is
subjected to a preliminary treatment with potassium iodide,
and silver reduced from the oxide by hydrogen is also service-
able; but the best form of silver, and the one most easily prepared
in the pure state, is that deposited electrolytically upon a small
oscillating cathode of platinum from a solution of silver nitrate,
the platinum anode bemg enclosed in a porous cell. The
shaking of the silver may be done by hand or by some simple
form of mechanical shaker like that described in the figure.
The time required for the absorption of approximately 0-658™
of iodine in 50°™* of liquid was 15 to 25 minutes. The mean
error of the eleven determinations in which electrolytic silver
was employed proved to be —0-00018™ between extremes of -
+0:0005 and —0-00048™.
To test the accuracy of the process in alkaline solution
experiments sinitlar to those above were made, in which the
TaBLe IV.
The Action of Silver upon N/10 Iodine in an Alkaline Solution.
Increase in
Silver Iodine weight of Error in Average
taken taken silver iodine error
grm. erm. erm. gTm. erm.
(A)
The action of silver shaken in air with NaHCO3.
2°0110 Orally 0°3221 + 0:°0004
3°6684 0°3217 0°3219 +0:°0002
3°0056 0°3217 0°3235 +0°0018
3°0093 0°3217 ' 0°3245 +0°0028
3°0058 0°3217 0°3224 + 0:0007
3°6686 O°3217 0°3243 +0:°0026
2°9993 Os 27 0°3261 + 0°0044
3°0013 Os 20g 0°3235 +0°0018
3°0014 0°6434 0°6485 +0:°0051 +0°0022
(B)
The action of silver shaken in an atmosphere of hydrogen with NaHCOs.
3°0014 0°3217 0°3216 —0:°0001
3°0169 0°3217 0°3216 — OL OOM
3°0083 06434 0°6433 —0°0001
3°0016 0°2500 0°2503 +0°'0008
3°0069 0°3217 0°3219 + 0'0002 +0:0001
Gooch and Perkins—Determination of Free Iodine. 39
mixture of silver and iodine was made alkaline by adding
about 10™* of a saturated solution of sodium bicarbonate.
The results of the experiments in Table IV, which show
irregularities when made in air and a very high degree of
accuracy when the shaking was done under hydrogen, prove
the absorption of iodine to be equally as exact in the alkaline as
the neutral solution.
The process described, in which free iodine is absorbed by
electrolytic silver under hydrogen, either in neutral solution or
in a solution made alkaline with an acid carbonate, should be
applicable in many analytical operations, as well as in the
gravimetric standardization of the usual iodine solution of
volumetric analysis.
40 Bowles—Pyromorphite from British Columbia, Can.
Art. VIL—Pyromorphite from British Columbia, Canada ;*
by O. Bow ss.
Introduction.—During the summer of 1907 Prof. W. A.
Parks of the University of Toronto visited the Society Girl
Mine in Southeastern British Columbia, situated a short dis-
tance east of the famous St. Eugene Mine in the Moyie Dis-
trict. Here he collected a large number of well-crystallized
specimens of pyromorphite, which were brought to the Min-
eralogical Laboratory of the University of Toronto, where the
writer was permitted to investigate them.
General description.—In this locality the pyromorphite is
found in association with galena and cerussite in the fractured
country rock. The cerussite and pyromorphite appear to be of
secondary origin through the decomposition of galena in frac-
ture cavities. A white clay surrounding the pyromorphite
crystals suggests the probable action of percolating water,
which may have supplied the phosphorus from organic matter
at higher levels.
The mineral occurs in the form of densely crowded erystal
ageregates. Most of the crystals are wax-yellow in color,
while some are ereen; and these two varieties exhibit some
interesting differences which are described later. The crystals
are brittle, of a resinous luster, and in their property of light
transmission vary from opacity or sub-translucency in the
larger to clear transparency in many of the smaller ones.
Crystallography.—The crystals are of one type only, being
prismatic or slender acicular in habit. ‘They occur in three
ways: (1) as separate individuals, (2) in radiating @ groups, or (3)
in tapering barrel-shaped agoregates. In some instances the
minute radiating erystals, crowded together over the surface,
possess a moss-like appearance. The needles may attain a
length of an inch or more, but those having faces sufficiently
bright to permit measurement with any degree of accuracy
are of almost microscopic dimensions. As the crystals are
very brittle and easily broken, it was a matter of some difii-
culty to obtain specimens with terminal faces. In small,
-well-protected pockets a considerable number were found, and
about forty-five were studied carefully on the two-cirele goni-
ometer of the Goldschmidt type.
Pyromorphite belongs to the hexagonal-bipyramidal class.
The forms observed by. me are as follows =
¢ {0001}, m{1010}, @ {1120}, & {1011)) > ey eoeiee
a \4041}, « 13034}, (See fig. 1)
* The data contained in this paper were embodied in a thesis accepted by
the University of Toronto for the degree of Master of Arts.
Bowles—Pyromorphite from British Columbia, Can. 41
The basal pinacoid, ¢ {0001}, is very poorly developed.
Reflections could be obtained from it on only five of the crys-
tals studied. On many of the crystals it was so rough and
uneyen that it appeared to be merely a
fracture surface. 7
The prism of the first order, m {1010},
is the most prominent form on all crystals,
and is usually represented by well-reflect-
ing surfaces, from which satisfactory read-
ings may be obtained. ‘These faces com-
monly exhibit minute longitudinal stria-
tions.
A very important fact which has not, to
the writer’s knowledge, been as yet ob-
served is to be noted in connection with
the prismatic faces. They do not exhibit an
absolute parallelism, but converge slightly
toward the upper end of the caxis. From
this it would appear that the symbol
41010} is only approximately correct, the
true prism faces being replaced by vicinal
planes which depart from the theoretical
position of the real prisms by a definite measurable angle. Only
in exceptional cases are true prism faces present, for almost
invariably they are replaced by these vicinal planes. The
readings for all the faces in the prismatic zones of twenty-one
crystals give a mean angle of 89° 33’ between the normal and
the. vertical axis. The Miller symbol thus becomes {135° 0°
135°1{. The frequent recurrence of these faces, indicating
an approximately constant deviation from the theoretical value,
gives weight to the theory of 8S. M. Websky,* that vicinal
planes are not accidental, due to distortion of the crystal, but
that they follow some definite law which has its foundation in
the internal molecular arrangement. In the table of angles it
will be noted that the other forms show considerable variation
from the calculated values also, but it must be remembered
that the values for these forms were obtained from poorly
reflecting surfaces, while in the case of the prism faces well-
defined images were obtained.
The prism of the second order, a@ {1120}, was observed on
two crystals only, the faces being very narrow, and in some
instances curved. As shown by the table on page 42, the read-
ings are, however, sufficient to indicate that the faces are
undoubtedly prisms of the second order.
The unit bipyramid, w {1011}, is the most prominent of all
the pyramidal forms. The faces are in most cases very dim,
* Zeitschr. d. d. Geolog. Ges., xv, p. 677, 1863.
42 Bowles—Pyromorphite from British Columbia, Can
and on the goniometer give no distinct signals. The bipyramid
y §2021t was found on three crystals only, and in each case
the faces were very indistinct. They are proportionally very
much smaller than the faces of the unit bipyramid. The
bipyramid 7 {4041} was observed with very narrow edges on
one crystal only. As no distinct images could be obtained
from these faces, several readings were taken, and the results
averaged.
The bipyramid ¢ {3034} isa new form. It was represented
on six of the erystals, and, though the faces are extremely
minute, the averages of a large number of readings approxi-
mate to the theoretical values so nearly that the form is estab-
lished with certainty. The average reading of four ot the best
faces gives a value 32° 28’ for the angle p, the caleulated value
bene (32> 31. ae form having this symbol is recorded for
apatite, which also belongs to the hexagonal- bipyramidal class.
The bipyramid of the second order, s 1212, is the only form
recorded by Dana or Goldschmidt ich finds no representa-
tion on these crystals.
All forms observed by me, as well as those given by Dana,
together with their calewated and observed angles, are
indicated in the following table :
TABLE OF ANGLES.
p 9
aa ahr = = =
Forms Ob- Calcu- Ob- Caleu-
Dana Bowles served lated served lated
e {0001} {0001} O° 08 0° ge naa
m {1010} {1010} 90° 03° 90° 0° 0°
Vicinal Soy Bey Cer eee On eee
q@ 41120} {1120} 90° 07' 90° 30° 04 tate
ea LOAM {1011} 40° 37’ 40° 22! Oty 0°
y {2021 12021} D9 NG. 59 32" OS 0°
a {4041} {4041} (OO (o> Be 0° 06’ 0°
Shea res NEL SU mile Oye Re a TENE 55° 49! Bee) 2 30°
rap mess Me. {3034} 32° 28) Bo Bil! 0°10 0°
Chemical Analysis.—As extremely pure crystals of both
the yellow and green varieties were at hand, it seemed advis-
able to make an analysis of each in order to obtain if possible
some adequate explanation for the variation in color. The
chemical analysis was, in general, based on the method outlined
bye Medicus.~ Whe results are as follows:
*Chemische Analyse; Kurze Anleitung zur Gewichtsanalyse, Dritte
Aufiage, p. 91, 1897.
Bowles—Pyromorphite from British Columbia, Can. 48
Yellow Variety Green Variety
TEEN ONY = ea ee 80°20% 80°13%
ia Orr a ees eyed 0°59 0°56
Pre Opps en. 5. Se RORSO 0°46
12)! ana ere 16°12 15°65
ANSE aS aati A Pel 0-41 0-90
OL a ante Cer ates 2°52 2°59
CA ee ee Fate oe trace ee
PSO] fore ste ee So = 0-08 0°05
100°78 100°34
Less oxygen equiva-
lentiet Chee te). 0°57 0°59
100°21 99°75
Although there is considerable difference to be observed in
the results of these two analyses, such as the striking variation
in the amounts of iron and arsenic, it can, nevertheless, be
shown that the analyses are to be relied upon; for if the mole-
cular ratios are calculated from the above determination, it will
be seen that in each case the results point to the generally
accepted formula for pyromorphite.
Yellow Variety Green Variety
Molecular Ratios Molecular Ratios
li VW IIT I II III
Fane) sj... 0°324 0°328
aerex sis: 0-010 0°346 9°03 0°010 | 0°340 8°95
BeOe re ., O'O12 0:007
iO. Rae EA a 0°0138 3°00 0110 3°00
0°115 0°114
As.O. ee 0°002 0°004
|2(015) Se 0-036 . 0°036 0°94 0:037 0°037 0°98
Since the combined molecular ratios of the oxides of lead,
calcium, and iron, and the pentoxides of phosphorus and
arsenic, are almost exactly in the proportion 3 to 1, we may
assume that those values are very nearly correct. Henceif we
give to the combined ratios of the pentoxides of phosphorus
and arsenic the value 3, we obtain the simplified ratios in
columns III. Im each case these are approximately 9: 3:1,
which, as remarked above, is in close agreement with the
generally accepted formula 9PbO.3P,0,.PbCl,, or in more
simplified form Pb,Cl (PO,),.
In some cases the green color has been accounted for by the
presence of a small amount of copper, but here no trace of
copper is to be found. Leonhard* states that the yellow
*N. Jahrbuch fiir Min. und Geol., 1867, p. 449.
44 Bowles—Pyromorphite from British Columbia, Can.
variety differs from the green only in its smaller content of
arsenic. He records an analysis which indicates that the green
pyromorphite contains 0°66 per cent arsenic pentoxide, while
the yellow variety contains none. The analyses given above
show a somewhat similar relationship ; for, although arsenic is
present in both, there is a larger per cent in the green
variety. ‘This’ fact, and the presence of a larger quantity of
iron oxide in the yellow variety, are the only marked ditfer-
ences brought out by the chemical analyses.
Specific ” Gravite y.—This was determined by means of
a Muthmann capillary-tube pyenometer. Extremely pure
material of both varieties was obtained, and a comparatively
large amount (about eight grams) was used, in order to imsure
accurate results. Crystal fragments about the size of fine shot
were employed. Several determinations were made, and the
results are tabulated below :
Yellow Variety Green Variety
De 2 Ree tare cts TO11 7°055
TRA eae eae 7°016 7°052
LUD) eee eae 7°012 7046
UA Aeepatiee soe ete ely) 7°014 7°053
INV CRA OC Matis Bie s 8 7013 7051
From the above results it is evident that the green pyro-
morphite has a higher density than the yellow. Dana* gives
the specific gravity of the pure mineral a rather wide range,
varying from 65 to 71. This British Columbian pyro-
morphite then approaches the higher limit set by Dana.
The results obtained are slightly higher than those of Bauer,+
who gives a variation of 6°9 to 7-0.
In conelusion I desire to acknowledge valuable assistance
rendered by Prof. T. L. Walker of the University of Toronto,
under whose direction the investigations were conducted. I
am indebted to Prof. W. A. Parks of the same institution for
selecting the material, and for information regarding its occur-
rence and associations.
Mineralogical Laboratory, University of Michigan,
Ann Arbor, Mich., March 8th, 1909.
* System of Mineralogy, p. 770.
+ Lehrbuch der Mineralogie, 2te Auflage, 1904, p. 800.
A. 0. Peale—Application of the Term Laramie. 45
Arr. VIII.—On the Application of the Term Laramie ; by
A. C. Prauu:
Two publications* by Mr. A. C. Veatch “ On the Origin and
Definition of the Geologic term Laramie ” seem to me to call
for notice because of an apparent misapprehension on the part
of Mr. Veatch of the origin of the name Laramie and as to
its use especially at the time it was given. It is also the more
necessary to come back to the original definition and applica-
tion because so many geologists "and paleontologists have
applied the name to beds that do not fall within the limits of
the definition. That corrections can now be made is largely
due to the discovery by Mr. Veatch in the Carbon and Evan-
ston regions of Wyoming of an unconformity just above the
beds that should be correctly referred to the Laramie in
accordance with the original definition, thus repeating west of
the Front Range of the Rocky Mountains the discovery made
by Cross and Eldridge of the Post-Laramie break east of the
mountains in Colorado in 1888+ and reiterated by them in
1896.
Witat I wish to show in this paper is, first, the original use
of the name Laramie; second, why the original name should
hold to-day just as when first defined; third, that the con-
clusions of Mr. Veatch, based as I think upon false premises,
are not verified by the facts; and fourth, that a new name is
not necessary even according to Mr. Veatch’s own supposed
evidence.
Asa member of the Hayden Geological Survey at the time
the term “ Laramie” was first proposed and used by both the
Hayden and the King organizations, and as one of those who
first used it, a statement of my recollection may be of some
interest here. Just at the time the work of the Exploration of
the 40th Parallel, under Clarence King, was approaching com-
pletion, and their geological maps were being colored, the
work of the U. 8. Geological and Geographical Survey of the
Territories had also reached the stage when it became neces-
sary to color the maps of Colorado, upon which field work was
begun in 1878 and finished in 1876. As two of the maps of
the former organization adjoined the work of the Hayden Sur-
vey along the northern line of Colorado, it was deemed desir-
able that there should be some correlation, in terms at least,
where the work joined. There was substantial agreement as
* This Journal, vol. xxiv, pp. 18-22 (an abstract), July, 1907; and Jour.
of Geol., vol. xv, pp. 526-549.
+ Proc. Colo. Sei. Soc:; vol. iii, p. 97.
¢U. 8S. Geol. Survey Monograph, vol. xxvii.
46 <A. C. Peale—Application of the Term Laramie.
to most of the formations, about the only difference being as
to the age of the beds resting conformably upon the Fox Hills
Cretaceous of Hayden as exposed along the line of the Union
Pacific Railway and to the eastward of the foothills of the
front range of Colorado, where they were usually designated
by Hay den and the members of his sur vey as the lignitie beds
of eastern Colorado or the lgnitie coal group of the eastern
slope. These beds were considered by King to be of Cretace-
ous age, while Hayden was inclined to consider them as belong-
ing to the Tertiary. At this time Clarence King wrote* to
Dr. Hayden asking him to propose a name for these debatable
beds—debatable only as to age, for both agreed. as to their
stratigraphic position. In reply to this letter Hayden sug-
vested the name Laramie, which was accepted by King as
indicated by him on page 831 of the volume on Systematic
Geologyt where he says: “‘ During the slow gathering of the
evidence which shall finally turn the seale, I proposed to Dr.
Hayden that we adopt a common name for the group, and
that each should refer it to whatever age his data directed.
Accordingly it was amicably agreed between us that this
series should receive the group name of Laramie, and that it
should be held to include that series of beds which conforma-
bly overlies the Fox Hills.”
In accordance with this, in coloring the geological map of
Colorado we designated the beds above the Fox Hills as
Laramie and in referring to their age called them Post-Ore-
taceous. There was no type locality so far as we were con-
cerned, nor was there any such idea in the mind of Hayden.
He proposed the name partly because it was a euphonious
name and a broad one as he conceived it, the beds outcropping
not only in the Laramie plains but also on both sides of what
was then sometimes known as the Laramie range, and also in
the vicinity of the Laramie River. It was also proposed by
him partly out of compliment to Clarence King, who was then
working in what Hayden termed the Laramie plains, he using
the term in its very broadest sense as reaching from the Lara-
mie Range to the Wahsatch Range.§
* Clarence King’s letter was found by the writer among the papers of Dr.
Hayden after his death. The name Laramie does not occur in it.
+ U. S. Geological Exploration of the 40th Parallel, vol. i, 1878.
t Dr. C. A. White, in an interview (March 24, 1909) with the writer, con-
firms the statement as to the origin of the name Laramie and says further
that the last time he talked with Dr. Hayden the latter protested against his
(White’s) having once used the term ‘‘ The Laramie Group of King,” when
he (Hayden) was the author of the name.
§ ‘This great area [Laramie Plains] might be called a park; it is enclosed
on three sides by extensive mountain ranges, but on the west its limits are
not well defined, inasmuch as no mountain ranges of any importance inter-
vene until we come to the Wahsatch Range in Utah.”—Report U. S. Geo-
logical Survey Wyoming for 1870 (1871), p. 121.
alt
A. C. Peale—Application of the Term Laramie. 47
He also believed that the ‘area for the solution of the
question [the relations of the well-defined Cretaceous group
with the Lignitic] lies in the Laramie plains and westward
towards Salt Lake.”’* It was intended that the name should
eover all localities in which the beds occurred. If any locali-
ties should be considered as typical localities they would be
those mapped by us along the Front Range in eastern Colo-
rado, and by King along the Range in Wyoming. That
Clarence King had no type localities of the Laramie plains in
his mind is also evident from the fact that immediately fol-
lowing his definition of the Laramie he gives as localities of its
occurrence the following in eastern Colorado, just north of the
area in which the Hayden Survey was at work :
°
Parks Station, Colorado,
6 or 7 miles west of Carr’s Station, Colorado,
West of Greeley, Colorado,
Crow Creek, Colorado, and
Platteville, Colorado.
These are followed by references to “good exposures of
Laramie” east of Separation, and at other localities along the
line of the Union Pacific and in northwestern Colorado.+
King refers to the exposures in Colorado as follows: ‘“ The
upheaved sedimentary rocks along the eastern foothills of
Colorado Range offer several admirable sections from the base
of the Cretaceous far up into the series, and these exposures
have formed the subject of continued study byes Eo Vv.
Hayden and the late Prof. F. B. Meek. ‘The section, as elabo-
rated by them, has been constantly re-observed by us with
such concurrence of result that we have cheerfully adopted
their nomenclature from the base of the series up to the sum-
mit as defined by them.’’t
King, after summarizing the Cretaceous series as defined by
Meek and Hayden up to and including the Fox Hill Group,
says:§
“ Here, with those who follow Hayden, the Cretaceous
series comes to an end. Conformably over this [Fox Hill
Group] lies the group which Hayden and I have agreed to
call the Laramie, which ts his Lignitic Group, and is con-
sidered by him as a transition member, between Cretaceous
*Aun. Rpt. U. S. Geol. and Geograph. Surv. of the Territories for 1873
[1874], p. 26.
+ It is interesting to note that Carbon, Wyoming, does not appear in the
list, and that Carr’s Station is only about 24 miles east of the lower end of
the Laramie hills, while the other localities are within short distances to the
east and southeast of the mountains.
¢ U. S. Geol. Expl. 40th Parallel, vol. i, Systematic Geology, p. 297.
$ Geol. Expl. 40th Parallel, Systematic Geol., vol. i, p. 848.
48 A.C. Peale—Application of the Term Laramie.
and Tertiary. There is no difference between us as to the
conformity of the Laramie Group with the underlying Fox
eile, wlite 1s simply a question of determination of age upon
which we differ.”
The italics in this quotation are my own. King is in error
as to the inclusion in the Laramie by Hayden of.the Fort
Union or of all the lignitic beds. Hayden’s last word on the
subject is the following :*
“Tf objection is made to the nse of the term ‘Lignitic’
Group I would say that, in this work, it is restricted to a series
of coal-bearing strata lying above the Fox Hills Group, or
Upper Cretaceous, and these are embraced in the divisions
Laramie and Fort Union Groups. It is well known that there
are in various parts of the West, especially along the fortieth
parallel and southwestward, very thick beds of coal in the
various divisions of the Cretaceous, extending down even into
the Upper Jurassic. Had this not been the case, the more
general term Lignitic would have been retained by this Survey
in preference to any other.” “It is also probable that the
Wahsatch Group as now defined and the Fort Union Group
are identical as a whole, or in part at least.”
Historically we find the first mention of the term Laramie
in an author’s proof of a Geological map No. II of the 40th
Parallel Survey. by Clarence King and 8. F. Emmons. This
map was dated November 15, 1875, and noticed in this Journal,
3d series, vol. xi, No. 62, p! 161, Feb. 1876. But neither on
the map, which covers the Green River Basin, nor in the
notice, is there any definition of the term. On the map cer-
tain areas are colored to represent the formation beginning
with the region to the west of Oyster Ridge, including the
vicinity of Rock Springs, Point of Rocks, and Black Buttes,
and extending on the east to Creston and a narrow strip of
country reaching southward from that station of the Union
Pacific Railroad. On the southern part of the map are sev-
eral small areas adjacent to the Uinta Mountains that are also
referred to the Laramie. It is noticeable that Carbon is not
included within the limits of the map. This map is referred
to by Hayden in his “ Notes on some Artesian Borings along
the line of the Union Pacific Railroad in Wyoming Territory,”+
in which article for the first time he uses the term Laramie,
which he does in strict conformity with the coloring of King’ S
map, which he evidently had before him as he wrote.
In this article also Hayden repeats his division of the Ter-
tiary into four series as laid down in his report for 1870 (p. 74),
the first two being the following :
* Report U.S. Geol. Survey of the Territories, Tertiary Flora, 1878, p. iv,
also p. Vv.
+ Bulletin U. S. Geol. and Geograph. Survey of the Territories, vol. iii,
No. 1, pp. 181-185, April 5, 1877.
A. C. Peale—Application of the Term Laramie. 49
“ First Series—The coal strata, Lower Eocene, character-
ized by numerous impressions of deciduous leaves, marine and
fresh water J/ollusca.
Second Series.—Arenaceous, Upper Eocene, characterized
by a profusion of fresh water shells, as Unio, Goniobasis,
Viviparus, Lymnaea, ete. and a portion of these being casts.”
On the next page, he says “The first series is the Laramie
or Lignitic Group; the second, the Wahsatch or Vermillion
Creek group, the former name having the priority, and:hav-
ing been attached to the great group of reddish sands, clays,
and conglomerates, west of Fort Bridger in 1870. This
group has been found to extend southward through western
Colorado into New Mexico.”*
As just noted, Hayden considered the Wahsatch and Fort
Union to be identical in whole or in part, a position that Dr.
Knowlton informs me was verified by him by his field studies
in 1908. In the diagrammatic section accompanying his paper
Hayden shows the Laramze divided into two groups resting
upon the Fox Hills.
The next one to use the term was Dr. C. A. White,+ who in
the same volume of the Bulletin gives two generalized sec-
‘tions; one of the Green River Region, in which he places the
Laramie Group in its proper place above the Fox Hills Creta-
ceous, and the other a section in the Upper Missouri River
region in which the Laramie does not occur, but in which the
Judith River Group is placed between the Fox Hills and the
Fort Union.
In the descriptive Geology, vol. 1, of the Reports of the
Geological Exploration of the 40th Parallel, which bears the
imprint of the year 1877, Mr. Arnold Hague gives on page 60
the first printed description ot the Laramie, beginning: “ The
Fox Hill strata pass by imperceptible gradations into the Lara-
mie series, offering no well-defined lnes of separation, both
formations from top to bottom consisting of coarse sandstone.”
Mr. Hague, after describing the geology of the Cretaceous
plains of Colorado, on the succeeding page (61) presents the
first section ever published of the Laramie which was measured
at the extreme northern limit of the Laramie formation about
18 miles southwest from Cheyenne, and 5 or 6 miles west
from Carr Station on the Denver Pacitic Railroad.
This section, if any should be so considered, would be the
typical Laramie section. Other Laramie localities east of the
Colorado Range and the Laramie hills he describes in follow-
ing pages. When Hague described the Carbon Basin it is
evident from the description (pp. 143-148) that considerable
* U.S. Geol. and Gcograph. Surv. Ter. Bull., vol. iii, p. 184.
+Ibid., No. 3, pp. 608, 609, May 15, 1877.
Am. JOUR. ae ae SERIES, Vou. XXVIII, No. 163,—Juxy, 1909.
50 A. C. Peale—Application of the Term Laramie.
doubt existed in his mind as to the exact age of the beds
exposed at Carbon. On p. 144 he says “In determining the
true horizon of these beds, however, it is necessary to trace out
their relations with the oreat sandstone for mation, which forms
all the higher ridges of the region, and to compare the strata
with other similar localities of Laramie or supposed Laramie
described in the remaining portions of the Report. In the
Annual Report for 1876 of the U. S. Geological and Geo-
graphical Survey of the Territories, published in 1878, the
reports of the geologists, which were prepared dnring the year
Si. all contain the term Laramie and the beds are repre-
sented and so named on the maps in the atlas of Colorado
which bears the imprint of 1877 although not actually issued _
until 1878.*
The Atlas of the 40th Parallel Survey, on which the Laramie
is also shown, bears the imprint of 1876, but was not issued
until a later datet+ (1877 or 1878 2).
It is evident, therefore, that the term came into use in both
the King and ‘the Hayden organizations at about the same
time.
Having given the facts as to the name and original use of .
the name “ Laramie,” I now wish to show that the definition
holds just as good to- “day as when made and that, notwithstand-
ing the mistaken application of the term to beds of older as
well as of more recent age, there still remains the set of beds
to which the name of Laramie was originally applied and to.
which no other name can logically be applied. As to the age
of the beds we are not primarily concerned in this place. As
Dr. G. M. Dawson said nearly thirty-five years ago,{ “ much
Of the Wditterence “Of “Opiniones pei ee “appears to have
arisen from approaching the problem with preconceived ideas,
and the attempted application of paleontological generaliza-
tions derived from the study of other localities, which have
been formulated under too rigid laws.” The confusion in the
use of the name is due mainly to the fact that not only have
the paleontological collections been too meager, but that the
stratigraphical relations have been misunderstood. Beds of
various ages have been mistakenly correlated as of Laramie
age without the confirmation of paleontological evidence,
although we now know that both stratigraphically and paleon-
tologically they are utterly different. Thus the beds at Point
* Catalogue of Publications of the U. 8. Geol. and Geograph. Surv. of the
Territories, 3d edition, p. 50, 1879.
+ Both the Hayden ‘and King Atlases are reviewed in this Journal, 3d
series, vol. xv, May, 1878, King” s on p. 396 and Hayden’s on Pp. 397. The
former is said to have been ‘ recently issued” and the latter ‘‘ just issued.”
+ Geol. and Resources of the Region in the vicinity of the Forty-ninth
Parallel, 1875, p. 184.
A. C. Peale—Application of the Term Laramie. 51
of Rocks, Wyoming, supposed by King to be of Laramie age,
were shown by Stanton* to belong to Montana. Cross and
Eldridge in 1888 described an unconformity above the Lara-
mie in the Denver Basin in Colorado and restricted the term
Laramie in accordance with its original definition to the beds
resting conformably upon the Fox Hills Cretaceous. The
Judith River beds, referred at one time or another to all the
formations from the Jurassic to the Fort Union, were finally,
in 1903,+ referred by Stanton and Hatcher to the Upper Cre-
taceous (Montana formation). More recently part of the coal
beds of the Raton Mesa region, studied by Mr. W. T. Lee,{
_have been found to be above an unconformity which apparently
occupies the position of the break found by Cross and Eldridge
‘above the Laramie in the Denver Basin. Mr. Veatch in his
generalized section§ in Carbon Co., Wyoming, shows an uncon-
formity separating 6500 feet of beds, which he calls ‘‘ Lower
Laramie,” resting conformably upon the Montana formation,
from 6000 feet of beds (called “Upper Laramie” by him)
tying conformably beneath strata of Fort Union age. The
beds just below the unconformity are devoid of plant remains
. so far as known at present. There certainly is room here for
the Laramie formation and the probabilities are that eventually
plants will be found in them and enable us to settle the ques-
tion of their age. The beds above the break and between it
and the Fort Union are in the Shoshone group as named by
Cross.| More recently Dr. F. H. Knowlton has determined
the Fort Union age of the Dinosaur (Ceratopsia) bearing beds
lying below the well-defined and almost universally recognized
Fort Union, by the identification of a typical Fort Union flora
associated with dinosaur bones. Knowlton has also referred
to the fact that the “ Upper Laramie” or Paskapoo beds of
the Canadian geologists are the equivalent of the upper Fort
Union and that probably their “ Lower Laramie” or Edmonton
beds should be correlated with the lower Fort Union, as both
of the latter also contain associated Fort Union leaves and
dinosaurian remains.** None of these supposed Laramie beds
of the Canadian geologists apparently conforms to the origina!
definition.++ It is doubtful if any beds of true Laramie age
*Science, N. S., vol. xviii, pp. 211, 212, 1903.
+U.S. Geol. Surv., Bull. No. 257, 1905.
t Lee, Bull. Geol. Soc. Amer., vol. xx, 1909 (in press).
§ This Journal, vol. xxiv, p. 18, July, 1907; also in Journal of Geology,
vol. xv, pp. 526-549, 1907.
| Proc. Washington Acad. of Sciences, vol. xi, pp. 27-45, March 31, 1909.
“| Knowlton, Proc. Washington Acad. of Sciences, vol. xi, p. 179 et seq.
** See, also, Geol. Surv. of Canada, Annual Report, vol. ii, for 1886,
p. 132, E. If not Lower Ft. Union, they may possibly be Shoshone.
++ McConnell in Geol. Surv. of Canada, Ann. Rept. for 1885, vol. i, 1886,
p. 46 C, refers to the ‘‘ Lower Laramie” as resting sometimes on the Pierre
shales but as occurring more often with Fox Hills beds intervening.
52 A. OC. Peale— Application of the Term Laramie.
occur in this region. In view of all these erroneous correla-
tions, inevitable though the mistakes were, and in view of the
present widely different application of the term as used by
various authors, it becomes absolutely necessary that we
should return to the original definition and confine the name
Laramie to the beds that fit the definition and apply it now
and in the future only to such beds. This is all the more
necessary inasmuch as the Laramie beds in the original or
typical areas in Oolorado east of the Front Range, although
restricted in thickness by Cross and Eldridge in taking from
the upper part (from above the break) the Arapahoe and Den-
ver, are characterized by a flora in which Dr. Knowlton rec-
ognizes 123 species, of which only 17 are common to the
Laramie and the Montana formations and 21 to the Laramie’
and the Denver. These beds also contain an imvertebrate
fauna of about 25 species of fresh and brackish water shells.*
As already noted also, there is according to Veatch a series
of from 4000 to 6500 feet of beds in the Carbon and Evans-
ton areas on the Union Pacific Railroad which occupy the
stratigraphic position of the Laramie above the Fox Hills, but
which up to the present time are not known to contain any |
fossil plantst but do have some fresh and brackish water shells
which alone are inconclusive as to the age of the beds.
After his introduction and a brief account of the confusion
in the present use of the term Laramie with a statement of
King’s views, Mr. Veatch gives his idea as to the boundaries of
the Laramie Plains based mainly upon descriptions by Prof.
Cyrus Thomas and Mr. Arnold Hague, and acknowledges that
the name has been applied in both a restrictive and a broad
sense, crediting Hayden with having used it in both ways.
Mr. Veatch then devotes seven pages to Hayden’s investiga-
tions, in which he quotes Hayden’s views as to the “ Lignitic
Group,” which is somewhat beside the question inasmuch as they
relate to what Hayden thought at various times between 1867
and 1875, before the term Laramie was i Then fol-
low five pages detailing Hague’s description of the Carbon area
and discussion of the age of the beds there exposed, and a
statement of ‘‘ Cross’s re- definition, ” after which he gives his
“summary and conclusions. These conclusions are identical in
his article and in the abstract in this Journal,§ and it is with
these alone that we are concerned here.
*U. S. Geol. and Geograph. Surv. of Territories, 11th Ann. Rept., 1879,
pp. 165, 190, 253.
+ In the Evanston area a few plants not specifically determinable have
been found.
¢t The Journal of Geology, vol. xv, pp. 526-549, 1907.
§ This Journal, voi. xxiv, pp. 18-22, 1907.
A. 0. Peale—Application of the Term Laramie. 53
~Mr. Veatch’s first conclusion,* that the name Laramie is
derived from the Laramie Plains, and his definition of the Lara-
mie Plains as extending from the Front Range to and slightly
beyond the North Platte River, have already been considered
in treating of the origin of the name on a previous page, when
it was also shown that Hayden was in the habit of using the
name in its broadest sense, comprising the entire country
between the Front or Laramie Range and the Wahsatch Range.
The second conclusion, that Carbon was a most important
locality both paleontologically and economically is undeniably
true ; but, although colored on the map as Laramie, the age of
the beds examined there was considered doubtful by King
and his colleagues I have already shown. It was geologically
considered by Hayden very much as by the members of the
King Survey. He says,t “ To the geologist this entire region
(from Carbon to Rawlins) is one of great interest. Even up to
the present time it is invested with much obscurity” ......
“The beds are so complicated” ...... “that it is difficult
to unravel their relations.”
That either Hayden or King had Carbon in mind as the
locality of a type section of the Laramie, is apparently a pure
assumption on the part of Mr. Veatch. Just as the geologists
of the King Survey had considerable doubt as to the geologi-
eal age of the beds of Carbon, although they colored them on
the map as Laramie, so King in his discussion of the Laramie
does not mention Carbon, nor does it appear to be mentioned
in the volume (Systematic Geology, vol. 1) and the name cer-
tainly does not appear in the index. The work of the Geo-
logical and Geographical Survey of the Territories did not
inelude Carbon, which was within the limits covered by the
Survey of the 40th Parallel, and all the work done there by
Hayden and his collaborators was simply in the way of recon-
naissance work and of the most general character.
The third conclusion of Mr. Veatch§$ contains three state-
ments that the facts scarcely warrant: first, that “It was the
practice of the Hayden and King surveys to name formations
and groups from localities where the beds were regarded as
typically exposed”; second, that ‘ the name Laramie was pro-
posed and adopted as an exact synonym of Hayden’s Lignitic
as defined by him in Wyoming and Colorado,” and third, that
“the type locality of the Laramie is Carbon on the Laramie
Plains.” :
Mr. Veatch himself acknowledged that ‘“ King used Green
River, Bridger, Uinta, Truckee, and other names without say-
* This Journal, loc. cit., p. 19.
+ This Journal, loc. cit., p. 19.
¢ Preliminary Rept. U. S. Geol. Survey of Wyoming, 1870 (1871), p. 1384.
§ This Journal, loc. cit., p. 19.
dt A. C. Peale—Application of the Term Laramie.
ing the name was derived from such and such a locality.”
Hay den did not aways give even names to the beds he studied,
as when in his earlier work he gave numbers to his subdivisions
of the Cretaceous. It was not therefore the general policy
of the Hayden Survey to name geologic formations from any
particular localities in which there were type sections. There
is no more warrant for assuming that Hayden, when he sug-
gested the name Laramie, had in his mind any type locality,
such as Carbon as sugested by Veatch, than there is for
assuming a type locality for the name Colorado, which was
applied by Hayden to the three divisions of the Cretaceous—.
Fort Benton, Niobrara, and Fort Pierre—on account of their
oreat variability j in western Coloradd and the difficulty of cor-
relating them with their equivalents in eastern Colorado.*
There was no type-section for the Wahsatch formation, the
name applied by Hayden to the variegated sands and clays
west of Fort Bridger and in the vicinity of Evanston. The
Fort Union Group was the name given by him to beds exposed,
not only in the vicinity of old Fort Union, but to those extend-
ing northward into the British possessions and southeastward
along the Missouri River as far as Fort Clark and as exposed
at various places in Wyoming. That there is no type section
_at old Fort Union I am prepared to say, after a personal exam-
ination of that region in 1907.
That the name Laramie was not used by Hayden as an exact
synonym of Lignitic is evident from what has already been
said under a previous heading, where it is noted that he
melted bork Laramie and Fort Union under the term Lig-
s, Lignitic was the broader term.
ea? s explorations began in the Upper Missouri Region
in 1855, and although he knew at that time that coal existed
in the Dakota group, for some time he regarded the entire Lig-
nitig group (excluding of course the Dakota coal).as of
Tertiary age. In 1868+ he recognized the existence of coal
beds extending into the Cretaceous, and in 1875, just before
the introduction of the term Laramie, came to the conclusion
that if a division of beds was based upon the presence of coal
a readjustment would necessarily follow. He says:{ “If it is
true that, taking into view the entire Lignitic area of our
western Territories, the coal beds are continuous in every
division, from the Jurassic to the suminit of the Upper Lignitie,
we might make this general division: Ist, Lower Lignitic group,
including all the Lignitic deposits of marine origin ; 2d, Middle
*U.S. Geol. Expl. 48th Parallel, vol. i, Systematic Geology, p. 298.
+ Bull. U. S. Geol. and Geograph. Survey of the Territories, vol. i, No. 2,
p. 1 B (prefatory note), 1876.
{ Bull. U. S. Geol. and Geograph. Survey of the Territories, vol. i, p. 406,
1876.
A. C. Peale—Application of the Term Laramie. 55
Lignitic, Gpaine all deposits of brackish water origin; 3d,
Upper Lignitic, including all beds of purely fresh- water origin.
In my opinion, the first division would include all beds to the
summit of the true Cretaceous; the Middle Lignitic embraces
my Transition Series, or, if they are not admitted by geologists,
I would insist upon their Lower Tertiar y age. The Upper
Lignitic, or fresh-water deposits, are of unquestioned Tertiary
age”. This makes it clear that Hayden did not intend to
include in the Laramie all the beds he had previously referred
to the Lignitic, not even his “Great Lignitic’”-—Cort Union)
being so included. The term Laramie was used by him and
by all the geologists of his survey to include the beds resting
immediately and conformably upon the Fox Hills. It was so
used in the Reports of the Survey and in the Atlas of Colorado,
as also by King and his colleagues in their reports and Atlas.
That Cross and Eldridge separated from the upper part of
the Laramie formation, as colored in the Atlas of Colorado,
the Denver and Arapahoe formations which were found
uncontormably resting upon the Laramie, and which they
divided into an Upper and Lower division, in no way invali-
dated its existence; nor do mistakes in correlation in other
localities of beds with the undoubted Laramie accor ding to the
original definition along the Front Range in Colorado, whether
made by members of the Hayden Survey in southern and
western Colorado, by King and his successors in Wyoming, or
by the Canadian geologists who call the Fort Union beds
Upper and Lower Laramie, destroy the validity of the term.
It would matter little if no Laramie were found in central
Wyoming below the great unconformity, where it may have
been removed by erosion, or that we find that we have to
extend the Fort Union downward and find it sometimes resting
unconformably upon Fort Pierre Cretaceous without Laramie
or even without Fox Hills beds beneath it. That we find in
Colorado, Wyoming and Montana a series of beds to which
local names have been given, such as Livingston, Denver,
Arapahoe, Black Buttes beds, Evanston beds and Carbon beds,
all of which he above the great unconformity and below the
Fort Union, and which cannot be correlated with either the
Laramie or the Fort Union, is a good and sufficient reason to
include them under the term Shoshone proposed by Mr. Cross.
It may be questioned whether the Black Buttes beds (Aga-
thamus beds) should be included in Cross’s Shoshone, but at
the present time the preponderance of evidence apparently
warrants such a reference. If the unconformity at the base of
these beds noted by Meek and Bannister in 1872 and Powell in
1876* should be fully demonstrated, the beds certainly could
* Geology of the Uinta Mountains, 1876, p. 72.
56 A. CO. Peale—Application of the Term Laramie.
not be correlated with the Laramie. Professor Meek,* basing
his opinion upon the study of the invertebrates, was inclined
to consider the beds as of Tertiary age, the Dinosaurian remains
alone indicating any other possible age for them. As to the
plants found at Black Buttes there are twice as many species —
common to these beds and the Shoshone as are common to the
Laramie and the Black Buttes beds, and we know now that
Dinosaurian remains are not uncommon in the Shoshone. If it
follows “irresistibly ” from what Mr. Veatch has written that
Carbon is the type locality of the Laramie, in my opinion it
follows just as “irresistibly” from what is outlined in these
pages that Carbon is not and never was the type locality.
Mr. Veatch’s fourth conclusion} is that the Hayden and
King parties at Carbon studied only the beds above the great
unconformity that he, Mr. Veatch, has since determined, and
that they considered them conformable to the Fox Hills, and
therefore according to Veatch these beds above the break and
these only should have the term Laramie. That King and
Hayden thought the beds conformable certainly justified them
in considering them at the time as Laramie 1n accordance
with their own definition and does not militate against the
reference to the Laramie of the beds below the break which
were not subjected to the same minute investigation as the
upper beds. <As to “the absolute necessity of a type locality
to afford the means of finally and conclusively correcting
inaccurate statements or conclusions of the author or authors
of a geologic name,” we at least all agree upon the desirability
of such a type locality, although we may disagree as to
whether there is one in the present case. Mr. Hague’s con-
sideration of the Carbon locality has already been referred to.
The fifth conclusiont of Mr. Veatch, that “the attempt to
redefine the term Laramie from the exposures in the Denver
region, some 200 miles from the type locality, is therefore not
defensible,” embraces several fallacies. In the first’ place
there was no redefinition, and secondly, as we have shown,
there is no specified type locality 200 miles from the Denver
region. If there were such a type locality the Denver region
would naturally be a part of it as already shown. No redefi-
nition of the Laramie was made by Cross and Eldridge when
they restricted it by taking from above it the Arapahoe and
Denver. No redefinition was necessary because of their dis-
covery of the unconformity at the base of the Arapahoe, for
the Laramie, although not so thick as first supposed, was still
left below, and was stilt conformable to the underlying Fox .
*U.S. Geol. Surv. of the Territories for 1872, 1878, pp. 529, 530.
+ This Journal, loc. cit., p. 20.
t This Journal, loc. cit., p. 20.
A. C. Peale—Application of the Term Laramie. 57
Hills, and the original definition still held good and would hold,
though only a few feet of beds had been left in that strati-
graphic position.
In his sixth conclusion® Mr. Veatch says, ‘“‘ while strictly
speaking the name Laramie can be applied appropriately only
to the upper beds (Upper Laramie) and it cannot with any
propriety be restricted to the lower beds (Lower Laramie), the
consideration that it was proposed for the beds between the
Wahsatch and the Marine Montana Cretaceous and has been
most commonly and extensively used in this broad sense, has
led to the suggestion that the retention of the name in the
original sense “will cause the least confusion, and that it there-
fore might be expedient to define the Laramie as that series of
beds occurring between the Marine Montana Cretaceous and
the Fort Union ”.
In the first place Mr. Veatch is not warranted in using the
terms Upper and Lower Laramie for his beds, as the Canadian
geologists have used these terms since the early eighties
(although they have misappled them). It is manifestly an
incongruity to include in the Laramie a marine or brackish
water series and a fresh-water series which are separated from
each other by an unconformity involving, as Veatch says, 20,000
feet of strata. As repeatedly shown in this article, the original
definition of the Laramie covers only the beds resting conform-
ably upon the Fox Hills. It was not proposed for the beds
between the marine Cretaceous and the Wahsatch, and if any
of the Fort Union or its underlying beds were included, it was
with the mistaken idea that the latter were conformable to the
Cretaceous beds below. Veatch’s redefinition of the term
would cause more confusion by far than by maintaining the
original definition and including in the Laramie beds only the
beds below the unconformity, resting conformably upon the
Fox Hills.
Bearing in mind the fact that Veatch always uses the name
Lower Laramie as the designation of the beds lying below the
great unconformity, | contend that even according to his own
presentation of the matter the term Laramie should apply to
them alone and that no new name is necessary. He sayst:
“There are reasons for believing that the enormous develop-
ment of Lower Laramie beds in the western part of the Lara-
aie Plans?’ 02. more completely represents the Laramie
deposition than at any other pot.” Why not therefore keep
the term Laramie for them so long as they coincide in strati-
graphic position with the beds that we know paleontologically
and stratigraphically to be Laramie east of the Colorado or
Front Range ¢
* This Journal, loc. cit., p. 20.
+ This Journal, vol. xxiv, p. 21, July, 1907.
58 <A. CO. Peale—Application of the Term Laramie.
Before concluding this paper the following point should —
e =) e
first be emphasized, viz., the importance of Mr. Veatch’s dis-
covery of the great uncon for mity lying above the Laramie, a
discovery the value of which ¢an hardly be overestimated.
As he himself s a “The discovery of this great unconformity
at all points that have been critically examined over an area
of 1000 miles north and south and 250 miles east and west;
the fact that it occurs on both sides of the Front Range of the
Kocky Mountains, and its great magnitude, all make it one of
the most important mile posts in the geological history of
western North America. All these considerations suggest
anew the first conclusion of Cross in the Denver Region, that
this unconformity marks the dividing line between the Creta-
ceous and Eocene in this region.” “Equally important with
this work of Veatch and of Cross is the identification by
Knowlton* of the lower Fort Union—the Dinosaur-bearine
beds of the Upper Missouri Yellowstone Region—and their
more southern extensions in Wyoming and the Dakotas. The
misapplication of the term Laramie to these lower Fort Union
beds of Knowlton and to the Shoshone beds of Cross was, as
already said, inevitable so long as we were in ignorance of this
great unconformity and the entire series was supposed to be
conformable. |
The one conelusion we come to from what has been detailed
in this paper is the following, viz., the name Laramie should
be used only in accordance with the original definition of King
and Hayden and be applied only to the beds resting conform-
ably upon the Fox Hills Cretaceous. Whenever we find beds
in this stratigraphic position they should be so referred,
especially if they contain a Laramie flora, as noted in the
original Laramie beds east of the Front Range in Colorado,
where there is also an invertebrate fauna comprising at least
‘twenty-five species of shells.
* Proc. Washington Acad. of Sciences, vol. xi, p. 179 et seq.
a
A. E. Verrill—New Genera and Species of Starfishes. 59
Art. 1X.—Descriptions of New Genera and Species of
Starfishes from the North Pacific Coast of America ; by
A. E. VERRILL.
[Brief Contributions from the Museum of Yale University, No. LXX.*]
THE species here described were mostly received from the
Canada Geological Survey; from the Provincial Museum of
British Columbia, through Mr. C. F. Newcombe; from the
U.S. National Museum; and from Prof. Kincaid, Washington
State University. More detailed descriptions and illustrations
have been prepared for publication in a General Report on
the Starfishes of that coast, from San Francisco to the Arctic
Ocean, which the writer has been engaged upon for several
years, and has recently completed, but its publication may be
somewhat delayed.
The littoral and shallow-water starfishes are probably more
abundant on the coasts of British Columbia and southern
Alaska than in any other part of the world. Of Asteriide
alone, there are at least 40 species, besides many named varie-
ties; of Solasteridee six species are recognized; of Pteraster-
idee seven species. A remarkable peculiarity is the number of
species having six or more rays, even in groups that are com-
monly 5-rayed.
Solaster galaxides Verrill, sp. nov. Figures 2, 2a,
A broad-disked species, usually with nine or ten rays, cov-
ered above with very small crowded pseudopaxille, and
resembling S. endeca in form and color. 3
Two typical specimens from Victoria have been received
from the Provincial Museum of British Columbia. Both
have nine rays. The larger has the radii 40 and 110™”; ratios.
about 1:2.7. It was orange in life.
There are usually two subequal, rather long, acute, diver-
gent Turrow-spines on.each adambulacral plate ; only one dis-
tally. On the actinal surface the curved transverse row or
comb has usually seven or eight graded spines, the two inner
decidedly longer and stouter. The marginal spines are about
as in S. endeca, but the infero-marginals are more elongated
transversely, and bear a decidedly greater number of more
minute spinules.
The synactinal series of pseudopaxille extends only to about
the basal third of the free part of the ray. They are rela-
tively smaller than in endeca, being here only about half the
* By an unfortunate error the Nos. LX VII and LXVIII of this series were
duplicated.
60 A. #. Verrili—New Genera and Species of Starfishes.
size of the infero-marginals proximally. The actinal inter-
radial areas are apparently relatively larger than in endeca and
bear a larger number of compressed pseudopaxille, the larger
ones similar to the infero-marginals and synactinals. They
form about sixteen radial rows, the smaller one in the median
rows distally. They are covered with a large number of small,
rather short regular spinules.
The oral and jaw-spines are much better developed than
usual. The four apical spines are very large, strong, and
res ale
Fig. 1.—Pteraster octaster V. Dorsal side; 2% nat. size.
acute. ‘There are six graded furrow-spines on each side.
The epioral spines are long and slender. They form two sub-
parallel rows of about eight or nine graded spines. The
spines in the opposed rows are often bent toward each other
and interlocked. The two most adoral are distinctly larger
than the others.
Soluster constellatus Ver., sp. nov. Figures 3, 4.
An 8-rayed species with a small disk and long tapered
Arms aadi are 21 and (8 "= mratios, aa.ie
The dorsal pseudopaxille are decidedly larger than in
Stumpsont V., which it somewhat resembles. They are stel-
late in form and usually, where largest, on the disk and base.
of rays, they have a single central and about six equally spaced
and webbed marginal spinules, which are often fully expanded
and nearly horizontal, producing the appearance of a six-
A. E. Verrill— New Genera and Species of Starfishes. 61
petaled flower; the largest ones may have seyen or eight diver-
gent spines, and the small distal ones only four or five; the
supero-marginal and actinal ones are quite similar. The infero-
actinal plates bear a larger number (8-12) of similar spinules.
The adambulacral spines consist of a furrow-series with two
or sometimes three rather short, tapered spines, and an outer
comb of six or seven nearly equal, tapered spines, webbed
nearly to the tips; the inner ones are usually rather longer, so
that the rows are a little graded. Adoral spines strongly
graded, about ten to a jaw, the apical ones unusually stout.
The type is from Puget Sound (Prof. Kineaid). This is the
only 8-rayed species known to me from that coast. Its large
and beautifully stellate paxillee are distinctive.
Pteraster octaster Ver., sp. nov. Figure 1.
Disk large and plump; margins well defined by points of
actino-marginal spines; rays eight, short, abont as wide as long,
subacute ; the ambulacral grooves turn up but little at the tips.
Radii of the largest example, 20 and 30”.
Dorsal surface covered with a thick membrane through
which the tips of the spinules show but little as pretty
uniformly scattered points; in alcohol they form the apex of
small, low, conical, fleshy elevations. Central oscule small, in
alcohol inconspicuous, its short spines covered by a soft mem-
brane. Ambulacral feet large, in two rows.
Adambulacral spines form combs of five or six spines, of
which the innermost is much smaller and more slender than
the rest, which are rather stout, tapered, subacute, divergent ;
the outer ones longer; the outermost appressed to the surface.
Epioral pair of spines long and rather stout, tapered, translu-
cent distally. The interradial areas are narrow, with rows of
long, stout, imbedded actino-marginal spines, the ends of which
project a little at the margin of the disk. Four specimens
were sent to me by the U.S. National Museum. Three were
from Bering Island, collected by Dr. Stejneger and Mr. N.
Grebnitsky in 1888. One was from Kamchatka, collected by
N. Grebnitsky.
This is the only Pteraster known which has more than six
rays and is therefore easily recognized.
Pieraster hebes Ver., sp. nov.
Disk plump and relatively large, the five rays being very
short and blunt, with the ambulacral grooves and plates turned
upward and reflexed upon the upper surface nearly to the base
of the rays, or about even with the shallow interradial angles.
Radii, 22 and 28™™. The central dorsal oscule is well devel-
62 A. FE. Verrill—New Genera and Species of Starfishes.
oped, surrounded with slender webbed, projecting spines in
five groups of eight - to ten each. The dorsal surface is covered
with a multitude of crowded slender spinules, which project
above the marsupial membrane and give almost the appear-
ance of velvet pile, but in some places they form more or less
evident divergent stellate clusters of twelve to twenty spinules.
Seen from within these spinules are slender, 2 to 3™™ long,
very divergent, supported by slender columnar paxille. The
HiGyeo:
Fig. 5.—Allasterias Rathbuni V. Dorsal view ; 14 nat. size.
ambulacral grooves aré broad and shallow. The ambulacral
plates are somewhat bilobed at the innér ends and distally are
somewhat imbricated. The adambulacral spines are long and
slender, about five or six in a transverse row, of which the
two inner ones are very small and slender, not half as long as
the outer ones, of which there are three or four, about 3°5"™
long. The appressed actino-marginal spines are distinctly
longer and about twice as stout and blunt proximally, but dis-
tally, on the upturned part, where they are crowded, they
become about equal in length to the adambulacrals and scarcely
A. FE. Verrill—New Genera and Species of Starfishes. 638
longer ; those near the interradial angles are flattened and
enlarged distally; the valves at the peractinal pores between
their bases are very acute, small, and slender.
Departure Bay, Br. Columbia, 23 fathoms, mud and sand,
1908 (C. H. Young), Canada Geological Survey.
Hippusteria spinosa Ver., sp. nov.
Very similar in form and size to . phrygiana of the N.
Atlantic, but thickly covered with large, tapering, acute spines,
usually one to nearly every dorsal plate and 1 to 3 on each
marginal. Many of the plates also have large elevated bivalve
pedicellariz, but not so wide as in phrygiana.
Departure Bay, British Columbia, 18 fath. (H.C. Young),
Canada Geol. Survey ; Puget Sound (Prof. Kineaid).
Tosia arctica Ver., sp. nov. Figures 8, 8a.
Pentagonal with short obtuse rays. Disk thick; margins
rounded. Radi 31 and 48™.
Dorsal plates, when granules are removed, are mostly ellip-
tical or rounded, well spaced ; granules are angular and coarse,
and those of adjacent plates are in contact in alcoholic speci-
mens, so that the plates mostly appear hexagonal or penta-
gonal; there are usually 6 to 8 marginal and one central
granule on the larger plates; some have, also, a bivalve
pedicellaria about equal to a granule in size. Marginal plates
not very large, closely and coarsely granulated ; the distal ones
become less regular, partly rounded, and small. Plates of
lower side uniformly coarsely granulated. Adambulacral
plates have two short, thick furrow spines and five or six on
outer part, often with a pedicellaria of similar size.
Bering Island (N. Grebnitsky, 1889). U. 8S. Nat. Mus.
Type.
Asterias (Pisaster*) papulosa Ver., sp. nov.
A very large 5-rayed species, with a high, swollen disk and
long tapered rays. adil of a medium-sized specimen, 42
and 210™™ ; ratios, 1:5; rays, 45™" broad at base, 438"™ high.
A larger specimen is 660" broad.
The dorsal spines are few, short, thick, tapered, subacute ;
they form simple median radial rows ; others are irregularly and
* This subgenus, or perhaps more correctly genus, first indicated by Mull.
and Tr. (type P. ochraceus), has monacanthid adambulacral spines and
remarkably large sessile denticulate pedicellariz, and usually, in the adult,
numerous rows of actinal plates and spines. P. papulosus is an exception,
as to the last character. It includes, also, P. fissispina, P. confertus, P.
Iutkeni, P. capitatus, P. brevispina and P. giganteus, all described by
Stimpson from the N. P. coast.
64 A. E. Verrilli—New Genera and Species of Starfishes.
Fig. 2.—Solaster galawides V. Profile view of adambulacral spines (a) ;
peractinals (6); marginals (c, d); and abactinals (e); x about 14 times.
Fig. 3.—Solaster constellatus V. Lettering as above; x about 10.
Fig. 4.—The same; some of the abactinal pseudopaxille# expanded, and
papular pores; more enlarged.
Fig. 6.—Allasterias Rathbuni V., var. anomala ; lettering as in fig. 2; a’,
furrow spines; p, p, major pedicellariz and papule. x about 6.
A. FE. Verrill—New Genera and Species of Starfishes. 65
distantly scattered ; distally somewhat in rows; also in ten
small clusters around the disk. Papuiar areas very large, with
very large dermal groups of minor pedicellariz, and also large
wreaths around the spines. Large wedge-shaped denticulate
dermal major pedicellariz are numerous. A simple upper
row of marginal spines like the dorsals ; infero-marginals much
stouter, two to a plate; two regular simple rows of similar
stout actinal spines, with many large denticulate pedicellarize
between them. Adambulacral spines long and slender in a
very regular simple row. Large clusters of major pedicellariz
of various sizes, large and small, are attached within the
ambulacral grooves. Vancouver I. (Prov. Muss, BoC.); British
Columbia (Canada Geol. Survey), and Puget Sd. (Prof. Kin-
eaid, type).
Allasterias Ver., gen. nov. Type A. Rathbuni Ver.
Remarkable for the arrangement of the adambulacral spines,
in several series, of which one is deeper within the groove on
alternate plates. Disk rather large, areolate. Dorsal ossicles
numerous, but small, arranged, both on the disk and rays, in a
reticulate manner around the papular areas, which are numer-
ous, and bear large groups of small papule. Spines numerous,
arranged irregularly, or placed around the papular areas, but
usually forming a median radial series. Upper marginal plates
rather large and stout, so as to form an angular margin, each
bearing several spines larger than the dorsals. Lower mar-
ginals not close to the adambulacrals, bearing in the type two
or three spines, longer than the upper ones. Actinals rudi-
mentary or lacking. |
Allasterias Rathbuni Ver., sp. nov. Figures 6, 7.
Rays five, broad at base and rapidly tapering to acute tips.
Radii, 25 and 100™™; ratios, 1:4. Small major pedicellariz
are abundant all over the dorsal and lateral surfaces.
The whole dorsal surface is conspicuously areolate or reticu-
late, the areolations mostly 1:5 to 2™" broad. The dorsal
spines are very sinall and numerous, sometimes almost lke
round or capitate granules, being scarcely higher than thick,
Fig. 7.—The same, var. nortonensis ; lettering as in fig. 6. x 6.
Fig. 8.—Tosia arctica V. Some of the dorsal interradial plates with
granules removed ; 8a, the same, some of the larger radial plates with
granules and a pedicellaria; others bared of granules and showing
papule ; much enlarged.
Fig. 9.—Tosia granularis, dorsal radial plates, magnified the same as
fig. 8a.
Fig. 10.—Asterias (Leptasterias) macropora V. Under side of ray of
d-rayed Alaska specimen, with spines removed, showing large size of
ambulacral pores; x about 2.
Am. Jour. Sct.—FourtH Serizs, Vou. XXVIII, No. 163.—Juxy, 1909.
5
66 A. EL Verrill—New Genera and Species of Starjishes.
but in other examples clavate or partly acute; they are
arranged in single rows on ail the ossicles, so as to form a
border around the papular areas; toward the sides of the rays
they are distinctly longer and mostly clavate or subacute.
The upper marginal spines form a wide band of small
crowded spines, five to ten or more on a plate. They are
larger and Jonger than the dorsals, and two or three times as
lone as thick, ‘mostly cylindrical or clavate, sometimes gouge-
shaped. Below this band there is a broad intermar ginal chan-
nel with large papular areas and numerous rather large,
pointed major pedicellariz. This channel rapidly widens at
the bases of the rays.
The lower marginals form a double‘row, mostly two to a
plate; they are similar to the upper ones, but longer and
mostly more clavate, often with gouge-shaped tips. Between
the upper and lower marginals, at the bases of the rays, a short
intermediate row of ossicles 1s sometimes interpolated.
Major or forficulate pedicellarie are usually everywhere
abundant, scattered over the surface, between the dorsal, mar-
ginal, and actinal spines, and especially on the lateral chan-
nels and interradial areas. The larger ones are compressed,
rather large, lanceolate or acute-triangular, with a sharp or
acuminate apex. Those that are scattered on the dorsal sur-
face are much smaller, unequal in size, but similar in form,
though less acute.
The type specimens are from Maloska (Prof. Kineaid).
Specimens of varieties have also been sent from St. Michael’s
Island (L. M. Turner), 1878, No. 3821; Norton Sound (M.
Murdoch), 1883, No. 7621, U. S. Nat. Mus. A. amurensis
(Lutk.) is probably an allied species. Dedicated to Mr. Richard
Rathbun of the National Museum.
Variety anomala V., nov. Figure 6.
This variety is remarkable for the very stout, crowded mar-
ginal and adambulacral spines, which are inflated distally and
obtuse, with the tips excavate or gouge-shaped. (See fig.)
areal spines are small and capitate, but larger than in the
type. Radii 23 and 87"™. St. Michael’s I. No. 3821, U.S.
N. M.
Variety nortonensis V., nov. Figure 7,
This differs from the type in having the dorsal spines longer
and more acute, and the infero-marginal and actinal spines
longer and more tapered. Norton Sound (Murdock). No.
7621.
A. F. Verrill—New Genera and Species of Starfishes. 67
Asterias (Urasterias) forcipulata Ver., sp. nov.*
A very large species, allied to UV. Linckw. Rays long and
slender, gradually tapered; length of ray, 525™"; breadth,
28™™"; disk small. Dorsal skeleton weak, with large papular
areas nearly concealed by vast numbers of unusually large
minor pedicellarie.
The dorsal plates are small, three or five-lobed or stellate,
each of the larger ones usually bearing a rather long tapered
subacute spine; these are well spaced and form about five
irregular or indefinite rows. The spines are surrounded by
wreaths of the large minor pedicellariz, but these also occur:
in larger clusters scattered over the integument between the
spines. Large major pedicellariz are also scattered over the
back; these are stout, ovate-lanceolate, with obtuse tips, which
are usually strongly denticulate.
On the sides of the ray and separated from those above by
a wide papular band there is a row of small, mostly four-
lobed marginals, usually bearing a single long spine. They are
connected to those above and below by weak transverse bars,
leaving large papular areas between. The spines are rather
longer and larger than those of the dorsal surface. Between
these and the adambulacral spines there is a single row of
stouter spine-bearing plates, the infero-marginals; each corre-
sponds to five or six adambulacrals. Most of these bear two
long, tapered spines, usually blunt and somewhat flattened or
suicate at the tips, rather larger than the upper marginals,
usually 7 to 8™™ long. Between their bases there are often
scattered large and strong, denticulate, major pedicellarie,
similar to those of the back, but mostly stouter and more
obtuse ; with these are some that are much smaller, lanceolate,
and subacute. ‘The large pedicellariz also occur on the naked
spaces below, both on the papular areas and on the adambula-
cral plates. ‘Phere are also some small synactinal ossicles con-
necting the peractinals with the adambulacrals, but not bear-
ing spines. The adambulacral spines form two regular close
rows, two on each plate; they are slender, tapered, mostly
flattened, subacute, about 5 to 55™™ long. The ambulacral
pores are large and form four rows. ~
The dorsal minor pedicellariz are remarkable for their great
size and abundance; in life they probably nearly conceal the
whole upper surface and spines, and are borne on slender
pedicels.
Departure Bay, Brit. Col., 18 fath., gravel (C. H. Young,
1908), Canada Geol. Survey.
* The subgenus Urasterias is now proposed for this species, with U.
Linckii and U. panopla Str. of the Arctic. Itis characterized by the absence
of spiniferous actinal plates, weakness of dorsal skeleton, great size and
abundance of both kinds of pedicellarie. Type U. Linckii.
68 A. &. Verrill—New Genera and Species of Starfishes.
Asterias polythela Ver., sp. nov.
Rays six, stout, of moderate length, rounded and with a
firm skeleton. Radii 20 and 80"; ratios, 1:4.
Dorsal surface appears rough and rugged. It bears an
irregular number of large, stout, round spines, arranged with-
out order, except that in a few places two or three may stand
in a median series; elsewhere they may be grouped, 2 to 5,
near together, or stand singly. These spines stand on raised
central bosses of the plates; they are constricted somewhat at
base and then abruptly enlarged below the middle; the termi-
nal part is regularly tapered or somewhat acorn -shaped or nip-
ple-shaped, longitudinally finely grooved, ending in a blunt
apex. They are 2 to 4™ high and 1:5 to 2™™ in diameter,
Scattered over the whole surface are many small, unequal, short,
acorn-shaped and capitate spines, mostly from 2 to, 4>™ in
diameter. The large and small spines are ali surrounded by
close wreaths of small minor pedicellarize; clusters of these are
also attached to the skin, so that the surface appears to be
almost covered with them.
The marginal and actinal rows of spines are pretty regular
and smaller than the dorsals. The upper marginals stand
mostly one toa plate proximally and two to a plate distally.
They are shaped somewhat like the large dorsals and nearly as
long, but only about half as thick. The lower marginals are
about as long, but stouter; they stand either one or “two to a
plate. A short row of smaller spines is interpolated between
the upper and lower marginals proximally. The peractinal
spines are like the lower marginals proximally and form a
regular. row, one to a plate. The adambulacral spines are
small, round, blunt, mostly two to a plate, sometimes one in
certain parts, divergent and almost concealed by large clusters
of small, ovate, major pedicellarie on the inner ones, and
clusters of major pedicellariz on the outer ones; many large
clusters of major pedicellariz are attached to the inner edge
of the plates within the furrow. A few much larger, blunt-
ovate, major pedicellariz with finely denticulate jaws, occur
on the interradial spaces and between the proximal marginal
spines.
The type was taken off the Arctic coast of Alaska by the
U.S. R.S. “ Gorwin” in 1885; No. 16889 (U.S: Nati
No. 15820).
Asterias victoriana Verrill, sp. nov.
The type of this species is from near Victoria, British
Columbia, sent by Mr. Newcombe. Radii, 20 and 95™™;
ratios, 1: 4°75. Rays five, stout, rather rapidly tapered. Dorsal
A. E. Verrill—New Genera and Species of Starfishes. 69
skeleton conspicuously reticulated, leaving large papular areas,
which are mostly rounded or somewhat elliptical, the trans-
verse diameter the greater. The intervening ossicles are strong
and prominent above the surface, as narrow convex ridges ;
those at the intersections and in the radial rows larger and
deeply four to six-lobed, convex in the middle, with a central
mammilla and pit where the spine is attached.
The dorsal spines consist of two very unequal kinds. The
Jarger ones are few in number and are widely scattered, except
in the median radial line, where they form a pretty "veoular
row; the others stand somewhat in quincunx, but may belong
to about three impertect rows on each side. These spines
stand on the larger plates at the intersections of the reticula-
tions. They are rather large, short, and thick, not much
higher than broad, with enlarged, truncate or capitate tips,
striated on the sides and rough on the top. They are about
1:5"" broad. Between these there are many very small incon-
spicuous spines, arranged mostly in single rows along the
narrow ossicles that form the sides of the reticulations. Some
of them are acute, but most are shghtly clavate with rough or
spinulose tips. Both kinds are scattered irregularly on the
central area of the disk.
Small minor pedicellariz are thickly scattered over the
whole surface between the spmes and on the papular areas,
and also form wreaths around the larger spines.
The supero-marginal spines form simple regular rows, and
are much like the large dorsals in length and form, but are
smaller. The inter marginal channel is well defined and of
moderate width. The infero-marginal spines form a regular
row, mostly simple, but frequently stand two on a plate dis-
tally. They are followed, proximally, by two pretty regular
close parallel rows of actinal spines, of about the same size
and shape. These three rows of ventral spines are longer
than the supero-marginals and less clavate, but about as stout.
They are blunt and sulcate at the tips. The first subactinal
row extends only to about the end of the proximai third of
the ray ; on the proximal fourth there is also a simple row of
synactinal spines.
The ossicles of the two marginal rows and next two actinals
are thick, nearly equal in size and form, and proximally stand
in four or five regular rows; the upper marginals are a little
more removed, but the others are closely united in a tessel-
lated manner , leaving only small papular pores between them.
The exposed ‘part is convex, with facets and pits for the spines.
They are shghtly four-lobed, but are so imbricated that they
appear squarish with rounded cor ners, or ovate-triangular.
70 A. &. Verrill—New Genera and Species of Starfishes.
The synactinal ossicles are smaller, with an oblong or ellipti-
cal surface, and mostly bear a single spine; they extend only
to about the proximal third of the rays.
The adambulacral spines stand two on a plate, or else in
certain parts one and two alternately, thus forming two or
three crowded rows. They are unequal, not very slender, the
inner ones slightly tapered, the outer ones stouter, blunt, as
long as the ventral spines, but more slender. They increase
somewhat in length and thickness toward the mouth.
The two apical preoral spines are rather stouter and shorter
than the adorals; their side spines are about half as long and
more slender. The epioral spines are like the adorals.
The adoral carina is rather thick and stout, composed of
three pairs of contingent plates beyond the epiorals, the third
pair bearing two spines. |
Major pedicellarie of moderate size occur among the ven-
tral spines and on the lateral and dorsal surfaces, but are not
numerous... They are compressed, lanceolate or acute-ovate,
with sharp tips.
J. A. Dresser— A Rare Rock Type. 71
Arr. X.—On a Rare Rock Type from the Monteregian
Hills, Canada; by Jonny A. Dresser.
[Published by permission of the Director of the Geological Survey of
Canada. |
Tre Monteregian Hills form a well-recognized petrographic
province* consisting of eight hills composed of igneous rocks
in the St. Lawrence valley extending along a line from Mount
Royal at the city of Montreal eastward for a distance of fifty
miles. They are a series of volcanic necks or laccoliths intru-
sive through Paleozoic sediments. The intrusions took place
probably in Devonian times, since which there has been a long
period of erosion succeeded by heavy glaciation, thus leaving
hills of the butte type and composed of plutonic rocks. They
are comparatively fresh and lend themselves particularly well
to the method of determination required by the Quantitative
Classification, which proves an invaluable aid in correlating
them.
The rocks of these hills are those characteristic of. alkalic
magmas and the province may be compared to that of Essex
county, Massachusetts, the Magnet Cove district, Arkansas,
the Crazy mountains of Montana, in the United States of
America, or to the Christiania district in southern Norway, or
the Kola peninsula, Finland. In each of the hills there is a
large development of essexite or theralite, and in all that have
been studied in detail an alkali syenite, pulaskite, nordmarkite
or nepheline syenite has been found. There is thus quite a
wide range of composition between the different rocks of the
individual hills. The mean composition of the hills compared
one with another also varies considerably, but this variation is
expressed in the different proportions of the essexite and
syenite groups rather than by the occurrence of widely different
rock types. The basic rocks are more extensively developed
towards the western end of the group.
St. Bruno Mountain is the local name of the second of the
Monteregian Hills from the western end. It is fourteen miles
east of Montreal, near the line of the Grand Trunk Railway
between Montreal and Portland or Quebec.
Many years ago a rock was noted from this hill by the late
T. Sterry Huntt+t to which he gave the name of “olivinitic
dolerite or peridotite,” and which is a somewhat different type
from any of the series yet described. Hunt observed that
olivine was the preponderating mineral in some portions of the
* Adams, F. D., ‘‘The Monteregian Hills, a Canadian Petrographic
Province,” Journal of Geology, vol. xl, No. 3.
+ Geolog y of Canada, 1863, p. 665 et seq.
72 J. A. Dresser—A Rare Rock Type.
rock. The writer in a recent examination, the resnlts of which
will be published in a report to the Geological Survey, did not
find any part of the rock so rich in olivine as that, but found
olivine commonly present up to 25 per cent, as well as could
be judged by the eye. The rock is dark greenish black or brown ~
in color. Pyroxene, olivine, biotite, sometimes feldspar and
usually specks of pyrrhotite can be distinguished in it by the
unaided eye. It is an even-grained, plutonic rock having a
rather coarse texture.
In the thin section it is found to be composed essentially of
pyroxene, olivine, brown hornblende, biotite, and labradorite.
The hornblende and biotite are often intergrown with each
other and sometimes with the pyroxene. The accessory min- —
erals, pyrrhotite, titanite and apatite, are in their characteristic
positions with the earlier constituents. The general order of
crystallization has, therefore, been—olivine and accessories ;
pyroxene; hornblende and biotite; feldspar. A fresh speci-
men, which did not represent the maximum content of olivine
seen, was taken and submitted for analysis to Mr. M. F. Connor
of the Geological Survey, Ottawa, Canada, who gives the fol-
lowing results in column I:
A* ey Ui III IV
SOs er saat 45°37 39°97 48°63 49°02
AL ORs sanG 2 | 8°68 5°32 10°14
KerO? 222s 240 8°63 291 1°54
HeOe 28:00 7.99 3 90 10°46
Mn@s-3s3 alte "19 a2 0°16
NiO + CoOy 17 B20 + hes. et eu! O11
Wore eA 18°67 10°32 on ak 17°25
CAa@ree 14°47 15°18 13°04 8°29
INaO 2") 585 119 "34 1°59
A OS BF 74 "23 0°40
OO Fanon: "62 1:15 cae ee
TiO ye doe MESO 4°05 “47 0°99
HOR ven Bess , "BT 2°81 0°75
99°75 99°39 100°13 Baers
*T Palisadose, St. Bruno Mt., Quebec, M. F. Connor, analyst. II Yamas-
kose (yamaskite) Mt. Yamaska, Quebec, G. A. Young, analyst. III Bel-
cherosé, Belchertown, Mass., L. G. Eakins, analyst. IV Palisadose
(olivine diabase) Englewood Cliffs, N. J., KR. B. Gage, analyst.
Calculating the molecular ratios in Analysis I and reducing
these to percentages of standard minerals, the norm is found
to agree so closely with the estimated mineralogical composi-
tion of the rock that it may be safely considered a normative
rock.
J. A. Dresser—A Rare Rock Type. 73
Norm
PAMOREMILE OS 2k 2 L. 12°23
pAMliionGe <a are)
iNepinelimness 2. —.. 2.5.7 2°18
Mromoclase 252 45... 32°22 .total’salie?. 2... 5k. 19°46
iDiopside- 2.2... .- 47°24
Orie a) Fo 2505
Miaenetite 222202 ..5: 3°48
Mimtenites 2 8-289, totalifemie sis. v2: 78°66
CO,, calcite being secondary ‘62
LE QO Ns bess ne ik "88
99°62
The rock thus falls m—
wc BSS, 1, We, ial a Re Ee ame ea fa Seah AS Dofemane
Order I[_. Peete te. Oe eee LRUMOArare
Section 2 (name proposed) eee ee Quebeciare
Rang 1 Og HANS RAS aR See EE es Ce (Quebecase
mecoion 2“ us ee Ee ee oR tase
Ona MOM rane wet Ak et leo: Tealisadose
The new names used above are proposed on the advice of
Professor J. P. Iddings and Dr. I’. D. Adams, to both of whom
the writer is indebted for advice in the matter.
A rock of closely similar composition has recently been
described by Professor J. Volney Lewis* from the Palisades
of the Hudson. Thisis a highly olivinitic facies of the diabase
of that well-known locality. An analysis of it is given in
column IV. From it the name Palisadose has been given to
the subrang of the Quantitative Classification, of which it was
the first representative rock described.
As the rock from St. Bruno is a distinct phase of the well-
defined petrographic province of the Monteregian hills in
- which allied varieties are likely to be found, it has been
thought that the larger divisions of the Quantitative Classifi-
cation might be suitably named as above proposed.
The nearest related rock in the Monter egian series, that has
thus far been described, is that named Yamaskite low Dirt Ge
A. Young from Yamaska Mountaint in which it oceurs. The
analysis of this rock is given in column IJ, while in column
IILis given an analysis of Belcherose from Belchertown, Mass.,
described by Professor B. K. Emerson (U. 8S. G. 8. Mono-
graph X XIX, p. 347, 1898).
McGill University, Montreal, Canada.
* Annual Report of the State Geologist of New Jersey for 1907, p. 124.
+ Report Geological Survey, Canada, vol. xvi.
14 Scientific Intelligence.
=
SCIENTIFIC [NDT EDRGUG EN Cm?
I. CHEMISTRY AND PHYSICS.
1. Cuprous Sulphate.—A. Recovura has succeeded in prepar-
ing this hitherto unknown salt, Cu,SO, Two complex com-
pounds of the salt, Cu,SO,.2CO.H,O and Cu,SO,.4NH, had been
prepared previously, but when attempts were made ‘to remove
the carbon monoxide or the ammonia from these compounds, the |
cuprous sulphate was decomposed at the same time. ‘The reason
for previous failures to prepare cuprous sulphate lies in the fact
that the compound is instantly decomposed by water, and it has
at last been prepared by the action of an anhydrous reagent,
methyl sulphate, upon cuprous oxide. The reaction produces
gaseous methyl ether as indicated by the equation Cu,O +(CH,),
SO,=Cu,SO,+(CH,),O. The reaction can be carried out with
great ease by heating finely pulverized cuprous oxide with a
large excess of methyl sulphate in a flask to 160° C. No precau-
tions for the exclusion of air are necessary, but the heating
should be stopped as soon as the evolution of gas has ceased, for
otherwise a second reaction sets in whereby the product is
changed to cupric sulphate by the action of the methyl sulphate.
The product is a.grayish white powder which is perfectly stable
in dry air. It is only slowly attacked by moist air under ordi-
nary conditions, but when it is wet with ether and the ether is
allowed to evaporate in the air, it is oxidized with great rapidity,
in a peculiar way, forming a mass as black as soot. This black
oxidation product when treated with water appears to yield the
black oxide Cu,O, which has been described by Rose, and cupric
sulphate. The unoxidized salt gives with water cupric sulphate
and metallic copper, a reaction which yields a disengagement of
heat amounting to 21 calories. This thermochemical relation is
opposite to that existing between cuprous and cupric oxides,
chlorides and sulphides, where the cuprous compounds are formed
exothermically.— Comptes endus, cxlviii, 1105. H. L. W.
2. The Action of Hydrogen Antimonide upon Dilute Silver
Solutions. —The familiar precipitate formed when hydrogen anti-
monide is passed intoa silver solution is usually regarded as Ag,Sb,
formed according to the equation H Sb +3AeNO, —Ag Sb+
3HNO,. A number of investigators, however, have been led to the
conclusion that the reaction is more complicated than the one
represented by this equation. HH. Reckiesen has recently made
a careful study of this reaction, and has found that in the first
place silver antimonide, Ag,Sb, is formed according to the above ~
equation, but that this precipitate then reacts to a considerable
extent with the excess of silver nitrate as follows:
Ag Sb +3AgNO,+3H,0=6Ag + H,SbO, +3HNO,.
Chemistry and Phystes. . 75
We have, therefore, as the final product a mixture of metallic
silver with much H,SbO, and little metallic antimony, while an
_ appreciable quantity of the antimonious acid goes into solution.
The reaction is precisely similar to that of hydrogen arsenide
_with silver solutions, except that in the latter case the arsenious
acid, being more soluble, goes into solution.— Berichte, xlii, 1458.
gy WA Ave
3. The Separation of Antimony and Tin.—G. Panosotow has
devised a simple and rapid method for the separation of these
metals, which can be used in all cases where the antimony is in
solution in the trivalent condition. To the solution is added
enough concentrated hydrochloric acid to give about 15 per cent
of the actual acid, then it is heated to 50-60° C. and a rapid
‘stream of hydrogen sulphide is passed in for 30 minutes. A
‘ yellow precipitate appears at first, but soon the cinnabar-red,
anhydrous antimony sulphide is formed, which settles rapidly.
The liguidis then cooled below 30° C., and a very moderate stream
of hydrogen sulphide is passed in for 10 minutes. Then the
precipitate is quickly filtered upon a Gooch crucible, washed with
15 per cent hydrochloric acid which has been saturated with
hydrogen sulphide until the tin has been removed, then the
hydrochloric acid is removed by washing with strong hydrogen
sulphide water. After this the antimonious sulphide is washed
successively with alcohol, a mixture of alcohol and carbon disul-
phide, alcohol, and ether. It is then dried at 110° and weighed.
The tin in the filtrate is precipitated with hydrogen sulphide
after partially neutralizing with ammonia, diluting with water,
and heating. Test analyses gave excellent results with widely
‘ varying quantities of the two metals.— Berichte, xlii, 1296.
3 Ele lies Wi.
4. The Purification of Sulphuric Acid by Freezing.—It is well
known that sulphuric acid containing about 94 per cent of the
_ “monohydrate,” H,SO,, yields crystals of the 100 per cent acid
upon cooling to about —20° C., and upon this fact is based a
method of concentrating such acid upon a commercial scale.
Morancé has found that a considerably weaker acid, if of just
the proper strength, will crystallize at a few degrees below zero,
and will yield a stronger and purer product than the original
material. In a case where an impure acid had been frozen so
that almost exactly equal weights of solid and liquid were pro-
duced, he obtained the following results upon analyzing the
products :
Crystals Mother liquor
fonited residues 2%. 22 2. 44,'.0°2320 0°5730
from-and alumina so =... 2: 0°0241 0:0825
Deyo 1) GS eae ee, Oe 0°0275 0°2250
DulpiuriG acide 2-4... 2 82°45 69:1
The results show a particularly good purification from arsenic
by the crystallization.— Comptes Rendus, cxlviii, 842.
H. L. W.
76 Scientific Intelligence.
5. Heat of Kormation and Stability of Lead and Silver Com-
pounds.—The impossibility of predicting from thermochemical
data the relative stability of similar compounds of lead and silver
has been shown by ALBERT Corson. It might be supposed that
the carbonate and nitrate of lead would be more stable than the
corresponding silver salts from the following heats of formation :
For PoCO 22 25 2 6660 Omer
or TA giC Oa aan ee eae 120800 - “
Difference 25. LS aie 45800 “
Kot Pbh(NO)) 322 ee ees Ae 5 40 Onecare
Ror Ao (NO) ot Se ee oat OO
Ditkerenee: 2.) apn et O00 Oma
Now while lead carbonate shows the expected greater stability,
as it was found to give a vapor tension of one atmosphere at
285° in comparison with 220° for silver carbonate, the nitrates
show an opposite relative stability, as lead nitrate gave off red
vapors at 283° while silver nitrate was not decomposed even at
350° ina vacuum. ‘The author has previously shown also that in
the general reactions of organic substances the results are not
necessarily governed by the maximum of disengaged heat.—
Comptes Rendus, cxlviii, 837. H. L. W.
6. efraction. of Réintgen Rays.—W. Wien and I. Stark
independently have shown that by the application of Planck’s
radiation theory to Rontgen rays one obtains wave lengths which
agree closely with the values 5-16.10-° cm. obtained by Haga and
Wind. In view of this B. Watter and R. Pout have renewed
their work upon the subject of the refraction of the rays, and do
not find any evidence of this refraction. If this does occur the
wave leneths must be less than 1°2.10-°cm. ; a suitably small
bundle of the rays through a slit 24 wide at a distance of 80 cm.
affords no evidence of refraction. Planck’s wave length deduced
from the quantity of energy theory is at the lowest 4°5.10-°em. The
authors conclude, therefore, that there is a discrepancy between
this theory and their observations, still to be investigated.— Anz.
der Physik, No. 7, pp. 331-3854. J. T.
7. Polarization of Roéntgen Rays.—In an investigation upon
this subject Haga has stated that the secondary rays are polar-
ized by a plate of carbon, and that these rays also are slightly
polarized by copper, aluminium and lead. He could not, however,
obtain any trace of polarization from the primary Rontgen rays.
J. Herweca is led to examine the primary rays proceeding from an
anti-cathode of carbon, and obtains evidence, in this case, of
polarization. He concludes that the rays from carbon differ in a.
marked degree from those coming from metals.— Ann. der Physik,
No. 7, pp. 398-400. JE
8. The Absorption of the y-Rays of Radium by Lead.—Various
observers have studied this subject, and have obtained exponen-
Chemistry and Physics. apt
tial expressions for the absorption with increasing thickness of
lead. Y.Taomrkosxt has used greater thicknesses of lead than
Rutherford, McClelland, Wigger and Eve. He finds that the
radiation after passing through a noticeable thickness of lead
does not diminish exponentially with increasing thickness of
lead.— Physik. Zeitschrift, June 1, 1909, pp. 372-874. J:
9. Use of Zine Sulphate in the Braun Tube.—The Braun
tube is of great use in the study of alternating currents and an
increase in the spot of light produced by the moving beam of
cathode rays on the fluorescent screen is very desirable from the
photographic point of view. F.Girsren and J. ZENNEcK describe
the use of zine sulphide, and show by photographs the advan-
tages of its employment.— Physik. Zeitschrift, June 1, 1909, pp.
377-379. Ta. We
10. Die Luftelekirizitdét. Methoden und fesultate der neu-
eren Forschung; von Dr. ALBert GockEeL. fp. vi, 206.
Leipzig, 1908 (S. Hirzel).—The problem of atmospheric electricity
entered a new phase with the discovery of the ionization of gases
by Rontgen- and Becquerel-rays and with Wilson’s observation
that gaseous ions may act as nuclei for the condensation of
water-drops. A great amount of work has been done in the last
ten or twelve years, especially by Elster and Geitel and their fol-
lowers, which will, doubtless, prove to be of great importance to
scientific meteorology. Dr. Gockel has done much work of this
kind, and in the present volume he gives a most useful résumé
of the methods and results of the modern investigations of this
complex and difficult subject. H. A, B.
11. La Materia Rudiante ei Raggi Magnetici ; by Auausro
Rieu. Pp. vi, 308. Bologna, 1909 (Nicola Zanichella).—This
volume (No. 12 of the series ‘“ Attualita Scientifiche”) begins
with brief account of cathode, anode, canal and Becquerel rays.
The greater part of the book is devoted to the so-called ‘ Mag-
netic rays” to which attention -has recently been directed, par-
ticularly by Villard. Professor Righi proposes the hypothesis
that these rays are streams of neutral pairs consisting of a positive
ion and a negative electron, rotating about each other. He has
made many ingenious experiments which are here described, and
which appear on the whole to lend support to his hypothesis.
There is a mathematical appendix in which the theory of the
motion of such systems is discussed. Ei; AGS TB:
12. A Text-book of Sound ; by Evwin H. Barton. Pp. xvi,
687. London, 1908 (Macmillan & Co.).—The author has assumed
on the part of the student no previous knowledge of sound and,
in mathematics, only a knowledge of the elements of the calcu-
lus. Nevertheless a student who reads this book will have an
extensive and satisfactory knowledge of all the essentials of the
subject. The dynamics of vibrating bodies and of wave motion
are neither shirked nor neglected, although (very properly) the
more intricate and complicated special cases are omitted. The
experimental side of the subject is well and fully treated and in
78 Scientific Intelligence.
general the book is an excellent example of what a text-book on
a physical subject for the use of serious students should be.
HB: A. B.
138. Applied Mechanics for Engineers ; by KE. L. Hancocex.
Pp. x1, 385. New York, 1909 (The Macmillan Co.).—The author’s
main purpose, as stated in his preface, is to emphasize the appli-
cations of mechanical theory to practical engineering problems.
This design appears to have been successfully carried out ; the .
numerous problems given are good examples of mechanical prin-
ciples and are at the same time stated in terms of angle-irons,
fly wheels, governors, and other concrete mechanisms. On the
other hand the physicist or mathematician will find much to com-
plain of in the loose and often imaccurate definitions and state-
ments of fundamental laws and principles. It would seem that
even for students of engineering a little more attention to logical
relations might be of value. 1B Ny 15)
14. The Absorption Spectra of Solutions ; by Harry C, Jonzs
and Joun A. ANDERSON. Pp.110 with 81 plates. Publication No.
110, Carnegie Institution of Washington, 1909.—This investiga-
tion is a continuation of the work of Jones and Uhler which was
begun in 1905 (see Carnegie Publication No. 60). The amount
of work performed by the authors is so great as to preclude the
possibility of doing it justice in this brief review. Nevertheless
the following salient points are especially worthy of notice.
The absorption spectra of solutions, in various solvents, of
twenty-four colored salts were photographed from A» 2000 to Ar
7400 and studied in detail. Some idea of the scope and thorough-
ness of the investigation may be formed from the fact that
about 1200 solutions were studied and that 1138 photographic
strips, each corresponding to a different solution, are reproduced
in eighty excellent, full-page plates. In general, the authors
have been able to draw definite conclusions as to whether a given
absorption band is due to ions, or to atoms, or to undissociated
molecules, and also as to the existence and relative importance of
solvates. Undoubtedly the most interesting and valuable results
were obtained in connection with the spectra of the three rare
earths investigated and especially in the case of neodymium
chloride. When this salt was dissolved in mixtures of varying
proportions of water and methyl alcohol it was found that the
apparent shifts in the bands were not real, as has usually been
believed heretofore, but that the effect observed is the result of
the superposition of two distinct sets of absorption bands, the
one set being identical with that exhibited by solutions in
pure water and the other by solutions in anhydrous methyl
alcohol. Ethyl alcohol and water gave similar results.
In conclusion, attention should be called to the source of ultra-
violet light used by Jones and Anderson, which is a marked
improvement over anything employed in the past. Taken as a
whole, Publication No. 110 is a valuable contribution to the sub-
ject of solutions and absorption spectra. |.) ERSeaGe
Chemistry and Physics. 79
15. Electricity, Sound and Light ; by R. A. MinurKan and J.
Mirus. Pp. 389. Boston and New York, 1908 (Ginn & Co.).—
“This book represents primarily an attempt to secure a satisfac-
tory articulation of the laboratory and class-room phases of
instruction in physics.” “It is designed to occupy a half-year
of daily work, two hours per day, in either the freshman, sopho-
more, or junior years of the college or technical-school course.”
This text-book supplements the course contemplated in Millikan’s
“Mechanics, Molecular:Physics and Heat.”
The authors have designed (and tested) the entire course in
such a wholesome, common-sense way that we are of the opinion
that an instructor who adopts their text-books and follows their
plans will approximate more closely to ideal conditions of teach-
ing-efficiency than can be attaied by the customary scheme of
independent class-room and laboratory courses. easy (0g
16. Hinfihrung in die Elektrotechnik ; by C. Hernxzu. Pp.
xix, 501; with 512 figures. Leipzig, 1909 (S. Hirzel).—This
text embodies, in an attractive and useful form, the author’s
course of lectures in the Munich Technical School; it is
designed as a connecting link between abstract electrophysics
and the technical applications of electricity. The subject matter
is treated under the following seven captions: Introduction ;
mechanical analogies helpful in comprehending the fundamental
phenomena of electromagnetism ; the generation of potential dif-
ference; the technical generation of electrical energy; the
utilization of electrical power by its transformation into other
forms of energy; electrical measuring instruments ; leads and
accessory apparatus. The discussions are direct and clear ; the
illustrations and mechanical features, without exception, excellent.
Topics of the articles are printed on the margin of the page, but
there is no index. Dak, Ke.
17. La Machine a Influence, son Evolution, sa Théorie; by
V.Scuarrers. Pp. vii, 506; with 197 figures. Paris, 1908
(Gauthier-Villars).—-The purpose of this book, as stated by the
author, is to assemble, codrdinate and perfect, so far as possible, all
of value that has been published on influence machines. A more
comprehensive and detailed description is given, of all of the
important influence machines, as well as of electrostatic motors,
than is to be found in any previous compilation ; and a serious
attempt is made to cover the theory of each part. The author
has made a number of original contributions to the subject. His
hydraulic models are of some interest ; but of doubtful value in
elucidating the principles of the machines. The results of a large
number of quantitative measurements are given, showing the
quantity of electricity produced per second, the potential differ-
ence maintained and the efficiency of the several types of
machines under varying conditions of atmosphere and manipula-
tion. In all probability the influence machine has attained, in
design if not in theory, its final stage of development ; in view
80 Scrventijie Intelligence.
of which fact this rather thorough compilation will prove of per-
manent value. It is much to be regretted that books of this
type continue to be published without an index. D. A. K.
Il. Grotocy AND NATURAL HIsToRY.
1. Publications of the United States Geological Survey,
GeEoRGE Oris Smiru, Director.—Recent publications of the U.S.
Geological Survey are noted in the following list (continued from
p- 406, vol. xxvii) :
Toroerapuic ATxLas. Twenty-eight sheets. |
Fouios.—No. 164. Belle Fourche Folio, South Dakota.
Description of the Belle Fourche Quadrangle ; by N. H. Darton
and C. C. OPHarra. Pp. 9, columnar section, 4 maps.
No. 165. Aberdeen-Redfield Folio, South Dakota. North-
ville, Aberdeen, Redfield and Byron Quadrangles. Description
of Aberdeen-Redfield District ; by J. E. Topp. Pp. 13, 12 maps.
Bu.yetins.—No. 373. The Smokeless Combustion of Coal in
Boiler Plants with a chapter on Central Heating Plants; by D.
T. Ranpaut and H. W. Werxs. Pp. 188, 40 figures.
No. 374. Mineral Resources of the Kotsina-Chitina Region,
Alaska; by F. H. Morrir and A. G. Mapprren. Pp. 103, 10
plates, 9 figures.
WatTER-SuppLy Papers.—No,. 223. Underground Waters of
Southern Maine; by Freprrick G. Criapp, with records of deep
wells by W.S. Baytry. Pp. 268, 24 plates, 4 figures.
No. 229. The Disinfection of Sewage and Sewage Filter
Effluents, with a chapter on the Putrescibility and Stability of
Sewage Effluents: by Harte’ Bernarp Puerps. Pp. 91, 1 plate.
No. 230. Surface Water Supply of Nebraska; by J. C.
STEVENS. Pp. 251, 6 plates, 5 figures.
No. 231. Geology and Water Resources of the Harvey Basin
Region, Oregon ; by Geratp A. Warine. Pp. 93, 5 plates.
Also advance chapters from Bulletin No. 380. Contributions
to Economic Geology, 1908, Part I.
2. Geological Survey of Canada, KR. W. Brock, Director.
Department of Mines, Geological Survey Branch. Ottawa,
1909.—The following publications have been recently received.
Summary Report of the Director for the Calendar Year 1908.
Pp. 220. This report contains a concise statement of the opera-
tions of the Survey for 1908. Some of the subjects discussed are
the following: The investigation of coal fields in the Yukon ; of
copper and gold deposits on Texada island; of the geology of the
southeastern part of Vancouver island ; investigation of the
Gowganda district in northern Ontario, which is a promising
silver camp, having some features in common with the celebrated
Cobalt region (see below). E. R. Fairbault notes that the valua-
ble calcium tungstate, scheelite, occurs somewhat abundantly at
a number of localities in the Moose river gold district, Halifax
county, N.S.
Geology and Natural Mistory. 81
Annual Report on the Mineral Production of Canada during
the Calendar Year 1906. Pp. 182.
Preliminary Report on Gowganda Mining Division, District of
Nipissing, Ontario; by W. H. Corus. Pp. 47, 7 figures and
map in separate envelope. . |
Report on Tertiary Plants of British Columbia, collected by
Lawrence M. Lamps in 1906, together with a Discussion of Pre-
viously recorded Tertiary Floras; by D. P. PENBaLLow. 4to,
pp. 167, 32 figures.
Contributions to Canadian Paleontology, Volume III, Part IV.
The Vertebrata of the Oligocene of the Cypress Hills, Saskatche-
wan; by Lawrence M. Lamsrx. 4to, pp. 64, 8 plates.
Two Geological maps of Hastings, Haliburton and Peter-
borough counties; by F. D. Apams and A. E, Bartow. Shu-
swap Sheet, British Columbia, 2 maps, G. M. Dawson and J.
McEvoy; map of southwest coast of Hudson Bay.
3. Geological Survey of Western Australia. Bulletin No. 32,
pp- 91, with 3 maps and 7 plates; by Harry P. Woopwarp,
Assistant Government Geologist. Perth, 1908.—This recent pub-
lication contains an account of the Greenbushes Tinfield; of the Mt.
Malcolm copper mine, Kulaminna; of Fraser’s gold mine, Yilgarn
gold field. The primary tin deposits occur in crystalline granite
rocks, which le within a belt of greenstone and greenstone
schists ; there are also secondary alluvial deposits. The amount
mined in 1906 was 783 tons and in 1907, 770 tons. Various rare
minerals occur with the tin ore, including tantalite, stibiotanta-
lite, microlite, gahnite, etc. It is noted, also, that particles of
undoubted metallic tin have been found, but it is suggested that
they may owe their origin to the action of bush fires on surface
exposures of tin ore.
4. New Zealand Geological Survey Department. Second
Annual Report (Nev Series), Wellington, 1908. Pp. 39, 8 plates,
2 maps.—This report gives a concise summary of the operations
of the New Zealand Geological Survey between January 1, 1907,
and May 31, 1908. It deals in part with the topography, in part
with the geology, including the economic side. An interesting
account is given of the survey of the Franz Josef and Blumen-
thal glaciers. The accompanying maps exhibit the portions of
the islands which have thus far been accurately surveyed.
5. Report of the Mineral Survey of Ceylon, James Parsons,
Principal Mineral Surveyor.—In addition to the general state-
ment in regard to the mineral production of Ceylon, this report
notes the discovery of a new locality of moonstone at Weragoda
in the Southern Province. Thus far practically the entire world
supply of moonstone has been obtained from the rock leptynite
in the Kandy district in Ceylon. At the new locality the moon-
stone is obtained by sinking pits in the swamp through some 4%
feet of black mud, when a white kaolin is obtained, which, on
being washed, yields the gems. It is probable that here, as in the
Kandy district, it is derived from a similar rock in situ, but this
Am. Journ. Sci.—Fourts SerRizs, Vou. XXVIII, No. 163.—Juny, 1909.
6
82 Scientific Intelligence.
is so much decomposed that the material can only be dug out
and washed.
In regard to the thorianite, the discovery of which excited
much interest some few years since, it is noted that the original
deposits in the alluvium have been practically exhausted. The
mineral evidently occurs in segregations in the pegmatite, which,
in decomposed condition, has been mined to some extent but not
thus far with important results. The quantity exported in 1907
was 10 cwt. valued at 4,750 rupees. It may be noted, also, that
the amount of mica exported from Ceylon in 1907 was 426 ewt.,
valued at 15,000 rs.; of graphite the amount was 650,000 cwt.,
valued at nearly 9,000,000 rs. The report closes with a list of the
mineral species known to occur in Ceylon.
6. Mineral Resources of Virginia; by Tuomas LEonarRpD
Watson, Ph.D. Pp. xxxi, 618, with 83 plates and 101 figures.
Lynchburg, Va. 1907 (J. P. Bell Co.). The Virginia-James-
town Exposition Commission.—This volume was planned in con-
nection with the Virginia-Jamestown Exposition, to call attention
to the remarkable resources of the state in its mineral wealth.
The state of Virginia has an unusually favorable position as
regards mineral resources, not only with respect to their diversity
and extent, but also the satisfactory conditions for work, due to
the mild climate and cheapness of labor, ‘There has been a very
rapid development in this direction within the past few years,
the production having increased three-fold from 1902 to 1906 ; in
the last-named year the total valuation of production having been
$30,000,000. Professor Watson is well equipped for the work he
has done here, and in preparing this volume he has made use of
the extensive material available on the subject from the reports
of Prof. Rogers in 1835 down to the publications of the present
time. He has also been aided by contributions from Dr. R. 8.
Bassler on cement and cement materials, by Prof. H. Ries on
clays, and by Prof. R. J. Holden on iron. The volume opens
with a brief statement of the general geology of the state,
with various columnar sections; this forms Part I. Part IIL
(pp. 16-187) is devoted to the building and ornamental stones,
cement, and clays; Part III (pp. 188-401) to non-metallic min-
erals, including pyrite, manganese oxides, mica, barite and gypsum,
coal, etc. ; while the closing part (pp. 409- 582) discusses in detail
the ores of iron, copper, zinc and lead, gold and silver. ‘The
volume is illustrated by numerous plates and maps, and cannot
fail to accomplish the object for which it was written.
7. Minerals of Arizona: their Occurrence and Association,
with Notes’ on their Composition ; Report to the Hon. J. H.
Kibbey, Governor of Arizona, by Wiruiam P. Briaxe, Territorial
Geologist. Pp. 64. Tucson, 1909.—Arizona has been so rich in
its mineral production that this concise account by Prof. Blake
of the species thus far discovered will be found most convenient
for reference by all mineralogists. It is noted that in 1908 the
copper production reached the large amount of 252,785,000 lbs.
Geology and Natural fistory. 83
8. Das Salz, dessen Vorkommen und Verwertung in Sdmt-
lichen Staaten der Erde ; verfasst von J. OTTOKAR FREIHERRN
Buscuman. I Band. Europa. Pp. xiv, 768. Herausgegeben mit
Unterstiitzung der K. Akademie der Wissenschaften in Wien aus
der Treitl-Stiftung. Leipzig, 1909 (W. Engelmann).—The second
volume of this exhaustive work on Salt was published two years
since (see volume xxii, p. 153), and was devoted to the various
countries in the world outside of Europe. The present ponder-
ous volume of nearly 800 large octavo pages is given to Europe,
and presents the facts with the same degree of thoroughness and
minuteness. The work is divided geographicaily according to
countries, beginning with Russia, after which follow Germany,
Austria-Hungary, Great Britain, France, Italy, etc. In each case
the same general heads are adopted, under which the multitude
of facts presented are arranged, viz. : The occurrence and exploita-
tion of salt ; the amount of import and export; the salt trade and
the use of salt. _ Numerous references to the literature open each
division of the work, and many explanatory foot-notes accompany
the text, adding to the completeness of the work as a whole.
9. Brief Notices of some Lecently Described Minerals.—
DELORENZITE is a titanate of yttrium, uranyl, tin and iron, per-
haps related to polycrase. It is described by Zambonini as occur-
ring in the pegmatite of Craveggia in Piedmont, sometimes
associated with stritiverite. Its crystallization is orthorhombic,
the crystals being slender, of prismatic habit ; hardness 5:5-6 ;
specific gravity 4°7; luster resinous; color black, in thin splinters
chestnut-brown. An analysis by Sterba gave:
TiO. 66°03 SnO. 4:33 UO. 9°87 Y20; 14638 FeO 4:°25= 99:11
From the above the formula 2FeO.UO,.2Y,0,.24T10, is calcu-
lated.—Zeitschr. Kryst., xlv, 76, 1908.
GEORGIADESITE is a chloro-arsenate of lead, described by Gau-
bert as occurring with other secondary lead minerals at the
ancient mines of Laurion, Greece. Crystallization orthorhombic,
crystals small, of short prismatic habit and hexagonal in aspect,
with m(110), 6(010), e(011), angle 6m = 60°1'; hardness 3°5 ; spe-
cific gravity 7°1; luster resinous ; color white to brownish-yellow.
An analysis gave:
AsO; 12°49 PbO 38°86 Pb 36°38 Cl 12°47= 100-20.
This is interpreted as Pb,(AsO,),.3PCl,, which brings it near
mimetite. Named after M. Georgiadés, Director of mines at
Laurion.— Dull. Soc. Min., xxxi, 86, 1908.
TARAMELLITE is a Silicate of iron and barium, described by E.
Tacconi from the granular crystalline limestone of Candoglia,
Valle del Toce, Italy. It forms columnar or radiated fibrous
aggregates of a brownish-red color; hardness 5°5 ; specific gravity
3°92. An analysis gave:
SiO, 36°56. Fe.O; 21°54 FeO 4°47 BaO 37°32 = 99°89.
The formula deduced is 4BaO.FeO.2Fe,0,.10810,. The mineral
is named for Prof. T. Taramelli.— Centralbl. Min., 506, 1908.
84 Scientific Intelligence.
TARBUTTITE is a basic zinc phosphate from the Broken Hill
mines in Rhodesia, described by L. J. Spencer. It occurs in
aggregates of small triclinic crystals, often forming an incrusta-
tion on limonite. The crystals vary from colorless to pale shades
of yellow, brown, red or green ; luster vitreous, but pearly on the
surface of perfect cleavage ; hardness 3°75; specific gravity 4°12.
An analysis gave : |
P.O; 29°2 ZnO 666 H.O 3:8 = 996.
The formula obtained is Zn,(PO,),.Zn(OH),. The mineral is
named for P. C. Tarbutt, who collected the specimens.
PaRAHOPEITE 1s from the same locality as tarbuttite; and is
also described by L. J. Spencer. It has the chemical composi-
tion of hopeite, but differs in physical and crystallographic char-
acters. It is triclinic, and is a little higher than hopeite in
hardness (3°75) and specific gravity (3°31). The same author
gives an exhaustive account of hopeite, distinguishing two varie- ©
ties, a-hopeite and B-hopeite.—Min. Mag, vol. xv, pp. 1, et seq.
RINNEITE is a chloride of iron, potassium and sodium, having
the formula FeCl,.3KCl.NaCl. It is described by H. E. Boeke
as occurrmg in coarse granular aggregates at the potash-salt
works in the southern Harz. It is soluble in water, having a
strong astringent ink-like taste; hardness 3; specific gravity 2°34.
The mineral is named after Geheimrat Rinne-Kiel.— Centrailbdl.
Min., 72, 1909.
10. Guide dans la Collection des Météorites avec le Catalogue
des Chutes représentées au Muséum. (Wdition A. Laxpar.) Pp.
iv, 58. Muséum Nationale D’Histoire Naturelle, M. Sranisias
Meunier, Professeur. Paris, 1909 (Laboratoire de Géologie du
Muséum).—The Museum of Natural History at Paris has, for
many years, possessed one of the great collections of meteorites
of the world. A considerable period has now passed since the
last catalogue was issued, and the present one, edited by Dr.
Labat, gives a total of 532 occurrences. The pages preceding
the catalogue proper are devoted to general subjects, including
the presentation of the well-known system of classification
advanced by Meunier. He recognizes 67 classes named from the
typical localities ; 28 of these fall among the irons, or siderites ;
10 to the lithosiderites, and the remainder to the stones, or
lithites.
11. Mendel’s Principles of Heredity ; by W. Barxson, F.B.S.,
Professor of Biology in the University of Cambridge. Cam-
bridge, England, 1909 (The University Press).—In the June
number of this Journal (p. 491), the present writer called attention
to this important treatise, and promised to notice further, in a
subsequent issue, the special contribution by Professor Bateson.
As is well known, this investigator has given much attention to the —
general subject of heredity, and has the distinction of having been
one of the earliest defenders of Mendel’s methods and views.
The defence was on the whole well conducted, but in the course
Geology and Natural History. 85
of it certain positions were taken which were later shown to be
untenable. From these positions, Professor Bateson has retreated
gracefully. In the present treatise he has endeavored to present
some of the more important facts relative to the study of certain
types, and this necessarily involves much condensation. It is
just here that the work strikes us as excellent in all respects. To
select from the rapidly accumulating stores of facts those
which are most telling, and to set these forth in a short yet clear
manner, is a task of great difficulty. It must not be expected
by the casual reader that a work on a topic so vast and recondite
as this will prove easy reading; it is not: but it is straightfor-
ward and free from unnecessary complications. Professor Bate-
son has here given some of the more interesting as well as
important studies in animals and plants, and has devoted a con-
siderable part of his space to color and color-ratios. It is this
which will open up to young naturalists an absorbingly attractive
field for original investigation. When one recalls the admirable
work which has been done by amateurs in the study of the rela-
tions of flowers to insects, it is not difficult to believe that this
neighboring field may receive assiduous cultivation at their
hands. To such, as well as to professional biologists, Professor
Bateson’s work will serve as an admirable guide, safe in all
respects. There is only one word of caution to those entering
this field of study: be as sure as you can that you know the
source of the material which you have under investigation. Do
not forget—what is too often forgotten—the difference between a
species and a race, and do not confound species-hybrids with the
crosses between races and between varieties. We do not mean,
of course, that we can as yet distinguish in all cases between
species and races, but we can at least choose as material
those plants about which there is comparatively little question.
In these days, when some of our polymorphous genera of plants
are in a state of disintegration, there is a large amount of good
material to be had. G. L. G.
12. Contributions from the Gray Herbarium of Harvard
University. New Series, No. X XX VI, May 1909.—This number
is given up to Mexican and Tropical American Phanerogams, and
comprises eight papers. Miss Alice Eastwood gives a synopsis
of the Mexican and Central American species of Castilleja, 54
in al]. Professor Robinson deals with the genus Rumfordia and
with a number of tropical phanerogams, some of which are new
and are now for the first time described, while others are trans-
ferred to their proper place in the system. Mr. H. H. Bartlett
treats of the American species of Litsea, the Mexican and Central
American Alders, the southern Androcerae, and certain other
southern flowering plants. These papers are published as No. 21
of Vol. XLIV of the Proceedings of the American Academy of
Arts and Sciences, Boston. Grin G.
13. Hlemente der exakten Erblichkeitslehre, von W. JouHANN-
SEN, Professor in Kopenhagen. Pp. vi,515. Jena, 1909. (Gus-
86 Scientific Intelligence.
tav Fischer.)—This volume of about 500 pages contains the
German translation of twenty-five lectures on heredity treated
from the modern standpoint of biometry. The author apologizes
for bringing so much that is mathematical into these discussions,
but he claims that he has reduced the mathematical difficulties to
a minimum. Certainly he has presented the subject with thor-
oughness, and has not avoided the hard parts of what is essen-
tially a very recondite matter. The historical development of
the subject takes it for granted that the reader (or hearer) prefers
to begin with nothing much farther back than Darwin and Wal-
lace, although the author refers to Lamarck and others before
him. Hence this treatise is practically an exhaustive résumé of
recent work, and as such will command serious attention from all
students of Genetics. The literature of heredity, of late, has
expanded enormously, and with comparatively little repetition
except in necessary citation, and promises to occupy soon the
greater part of the field of biology. In reading the most recent
works on this subject, one can hardly fail to be struck by the
important bearing the study of descent has upon the hard and
fast lines of many species which seemed to be safe within the con-
ventional limits. The examination of variant forms in polymor-
phous groups is working present havoc in systematic biology,
and no one dares longer to give the number of species belonging
to a genus ; but it is all in the direction of advance. ‘The pres-
ent work by Professor Johannsen is a long step in that direction.
G. L. G.
Ill. Miscenuanetous Scientiric INTELLIGENCE.
1. Publications of the U. S. Coast and Geodetic Survey, O.
H. Tirrmann, Superintendent. Results of Observations made at.
the Coast and Geodetic Survey Magnetic Observatory at Chelten-
ham, Maryland, 1901-1904; by Daniex L. Hazarp. Pp. 206,
56 figures. The same at Baldwin, Kansas, 1901-1904. Pp. 138,
4 figs.; at Sitka, Alaska, 1902-1904, pp. 129, 52 figs. ; at Honolulu,
Hawaii, 1902-1904, pp. 130, 53 figs.; at Vieques, Porto Rico,
1903-1904; pp. 70, 2 figs.—The series of volumes, noted above,
has recently been issued giving the results of observations made
at our various magnetic observatories. It was not until 1899
that the Government appropriations were such as to allow of a
systematic magnetic survey of the country, and the establish-
ment in connection with this of magnetic observatories. The
first complete observatory at Cheltenham, Md., 14 miles south-
east of Washington, was begun in 1900 and completed in April,
1901. Observations were also made at Baldwin, Kansas, begin-
ning in June, 1900, and in 1901 observatories were constructed at _
Sitka, Alaska, and near Honolulu, the records of which began in
1902. In February, 1903, observations were begun at Vieques,
Porto Rico, where, four years later, a special building was con-
Miscellaneous Intelligence. 87
structed. The five volumes by Daniel L. Hazard of the division
of terrestrial magnetism give the details in regard to these sev-
eral stations, with the observations that have been carried on
through 1904. An interesting series of charts is included giving
the records of magnetic storms, some of them of exceptional
intensity, which can thus be compared at the different points.
2. Hypsometry: Precise Leveling in the United States, 1903-
1907. With a Readjustment of the Level Net and Resulting
Elevations ; by Joan F. Hayrorp and L. Prxe. Pp. 280.—Fol-
lowing the publications on leveling by the U. 8. Coast and Geo-
detic Survey, given in Appendix 8 for 1899 and Appendix 3 for
1903, the present paper gives in detail the progress made in
developing the level-net over the country. Since 1903, 2,500
miles of leveling have been added by the Survey, and 1700 miles
by other organizations. Of these, two lines in Minnesota and
two in Louisiana, with a total length of 314 miles, are spurs from
the net, while all other lines form. links, or parts ‘of links, of the
net itself. A special chart shows the status of the net for 1907.
3. Bureau of American Hthnology, Smithsonian Institution.
—The following publication has been recently issued :
Bulletin 34. Physiological and Medical Observations among
the Indians of Southwestern United States and Northern Mexico ;
by ALES HrpiicKa. Pp. ix, 400 with 27 plates and 2 figur es.
Washington, 1908.
4. The Museum of the Brooklyn Institute of Arts and
Sciences.—The following has been recently issued :
Science Bulletin, Vol. I, No. 15. New Coleoptera, chiefly from
Arizona; by CHARLES SCHAEFFER. Pp. 375-386. April, 1909.
5. Report of Proceedings of the American Mining Congress.
Pp. 268. Denver, 1909.—This volume gives a report in detail
(pp. 1-122) of the proceedings at the eleventh annual session of
the American Mining Congress held at Pittsburg, December 2-5,
A series of papers, beginning with the annual address of the
president, Hon. J. H. Richards of Boise, Idaho, fill the 268 pages
of the second part. Among the papers may be mentioned accounts
of the mineral resources of Arkansas, Arizona, Virginia and
Alaska, and also a series on the conservation of mineral resources,
conservation in the coal a mining industries, ete.
6. Publication of the Works of Amedeo Avogadr 0.— The year
1911 will be the one- ec anniversary of the publication of
Avogadro’s classic memoir upon the molecular constitution of
gases. The Royal Academy of Sciences at Turin proposes to
celebrate the occasion by the publication of a volume containing
his most important works and by the erection of a monument to
him at Turin. The Committee of the Academy appeals to all
chemists and physicists to aid in this movement to honor the
memory of a man to whom Science owes a great debt. The
President of the Executive Commission is Sen. Enrico D’Ovidio
of Turin. The members of the Committee in the United States
include the following: F. W. Clarke, W. W. Coblentz, Ar.
88 Scientifie Intelligence.
Michael, A. A. Michelson, K. W. Morley, J. U. Nef, A. A. Noyes,
F. Nichols, I. Remsen, Th. W. Richards.
7. Proposed Publication of the Works of Leonhard KHuler.—
The. Swiss Society of Natural Sciences has issued a circular ask-
ing for contributions to aid in the publication of a complete edi-
tion of Euler’s Works; these may be made either as definite
donations or as annual contributions for a series of years. It is
planned to issue 40 volumes at a maximum cost of 25 francs.
The entire amount needed is estimated at 400,000 franes, of which
it is thought that 150,000 francs will be realized from the sale of
the books. This important movement has the sanction of the Inter-
national Congress of Mathematicians, the German Mathematical
Association, the French Academy of Sciences and other scientific
bodies.
Donations, as also subscriptions for the volumes as issued,
should be sent promptly to the President of the Kuler Com.
mittee, Prof. Dr. F. Rudo, Dolderstrasse 111, Ziirich V., Switzer-
land.
8. Prizes offered by the Austrian Society of Engineers and
Architects—The Osterreichischer Ingenieur und Architekten-
Verein at Vienna offers prizes of 3000, 1000 and 500 krone for
the solution of the following problem : “ Wie schtitzt man sich
vor den schadlichen Wirkungen der in den Wechselstromnetzen
dauernd oder zeitweilig auftretenden sogenannten hédheren
Harmonischen der Strom- und Spannungswellen oder wie unter-
driickt man deren Entstehen tiberhaupt ?”
Solutions must be handed in on October 1,1910. The special
conditions attached to the contest may be learned on application to
the management of the Society at 9 Eschenbachgasse, Vienna I,
Austria.
9. Psycho-Biologie et Energetique, Essai sur un Principe de
Méthodes intuitives de Calcul; par M. Cuartes Henry. Pp.
216, with 63 figures. Paris, 1909 (A. Herman et fils, 6 rue de la
Sorbonne).—This is a mathematical discussion, having as its
object the application of the principles of energy to the relations
existing between the senso-motor reactions of an organism to its
excitant.
10. Die Hinheit des physikalischen Weltbildes ; von Professor
Max Pruanck of Berlin. Pp. 38. Leipzig, 1909 (S. Hirzel).—
The address held on December 9, 1908, before the scientific
faculty at the University of Leiden is given in this little pamph-
let. It deals chiefly with the subject of conservation of energy
and its application to thermodynamics.
11. Phrenology: or the Doctrine of the Mental Phenomena ;
by J. G. Spurzuxrm, with an introduction by Cyrus ELpsER.
Yevised edition from the second American edition, in two vol-
umes, published in Boston in 1833. Pp. 459, with 14 plates. —
Philadelphia and London, 1908 (J. B. Lippincott Co.).—“ An
accessible authoritative statement of the principles of Phrenology
is needed, and will be found in the following treatise, which is as
simple, clear, and logical as any elementary work in any other
science.’ Introduction, p. 29, WwW. B.C
S/VOL. XXVIIL. | AUGUST, 1909.
Established by BENJAMIN SILLIMAN in 1818.
AMERICAN
JOURNAL OF SCIENCE.
Epirorn: EDWARD S. DANA.
ASSOCIATE EDITORS
Proressors GEORGE L. GOODALE, JOHN TROWBRIDGE,
W. G. FARLOW anp WM. M. DAVIS, or Camsrwncz,
Proressorss ADDISON E. VERRILL, HORACE L. WELLS,
L. V. PIRSSON anp H. E. GREGORY, or New Haven,
-Proressor GEORGE F. BARKER, or PHILADELPHL,
Proressor HENRY S. WILLIAMS, or ItHaca,
Proressor JOSEPH S. AMES, or Bautimmore,
Mr. J. S. DILLER, or Wasuineron.
FOURTH SERIES
VOL. XXVITI—[W HOLE NUMBER, CLX XVIII.)
No. 164—AUGUST, 1909.
NEW HAVEN, CONNECTICUT.
19.09.
THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 123 TEMPLE STREET,
Published annie Six dollars per yéary sponta tart ig6, 40. to sone in “tite
Postal Union ; $6.25 to Canada. Remittdncé$ should be made e ‘ier by ae, orders,
registered letters, or bank checks (preferably on New York banks).* |
AUG 141909
Mee Ne
REMARKABLE COLLECTION
We have secured some exceptionally fine minerals collected by an
American professor of national repute; it is beyond doubt the finest col-
lection we have yet handled. Lists are in preparation and will be sent only
on application. Owing to the lack of space can only name a few below.
Diamond, Brazil; different forms of xls. Native Tellurium, Colorado :
specimen 4 x 314, weighs 214 lbs; 316 x 31g; 316 x 3; the above telluriums
are the richest in existence. Sylvanite, Transylvania; very rich specimen
51g x 314. Native Gold, 5x 6x41, Cal. Native Iron (Terrestrial) in
basalt, Greenland. Meteoric Iron, Coon Butte, Ariz.; Pultusk, Pcland.
Iridosmime, Urals ; Orpiment, Utah ; Chalcocite, Cornwall; Livingston ite,
Mexico; Lorandite with realgar, Macedonia; Pyrargyrite, with tetrahe-
drite, Landu Hill; Argyrodite, Freiberg ; Cerargyrite, Chili; Embolite,
New Mexico; Iodyrite, Broken Hill; Quartz (Fulgurite), Poland ; Plattner-
ite, Idaho; Calcite, Iceland, 4.x 3, choice spec.; Parisite, S.A.; Pollucite,
Mount Mica; Eudialyte, Greenland; Meliphanite, Norway ; Gadolinite,
Sweden; Thorite, Norway; Apophyllite, and Stilbite, Bombay ; Harmo-
tone, Scotland ; Microlite, Amelia Court House; Columbite, Monazite,
Uraninite, Conn.; Pyromorphite, Cumberland ; Pyromorphite, rare form of
xls.; Vanadinite, Wanlock Head, Scotland ; Pseudomalachite, Rheinbreiten-
bach ; Chalcocite xlzd, Conn., choice; Crocoite, Cornwall; Libethenite,
Hung.; Erythrite, Thuringia; Arsenopyrite, Freiberg; Chrysoberyl twin,
Conn.; Stibiconite, Nev.; Pharmacosiderite, Cornwall.; Cuprite, pseudo,
France; Spinel, Monroe, N. Y.; Pyrosmalite, Sweden; Euclase, Brazil—Ural;
Canérinite, Norway; Sphene, Tyrol; Emplectite, Saxony ; Emerald in
matrix, Aquamarine, Alexandrite.
NEWLY DISCOVERED MINERALS AND
FROM NEW FINDS
Calciovolborthite, xlzd, Telluride, Colo.; Carnotite, Colo.; Patronite,
S. America; Goldschmidtite, Colo.; Apatite, Mesa Grande ; Bornite, Tyrol];
Tourmalines, emerald-green gem xls., Southern Cal.; Vanadinite-Smithson-
ite, N. M. |
A REMARKABLE CERUSSITE
We have on exhibition the largest and finest twin Cerussite in the
world. All its planes are finely developed. The crystals measure 7 inches
in length, 314g inches in width, and 44 inch in thickness. The erystal is
transparent, and its structure is beautifully displayed. Photograph and
particulars on application.
Will send box on approval by request. Further particulars cheer-
fully furnished.
A TH PEPEREIS,.
81—83 Fulton Street, New York City.
Bit
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THE
AMERICAN JOURNAL OF SCIENCE
fPEOURTH SERIES: ]
0 ——--—
Arr. XI.—On the Electric Arc between Metallic Electrodes ;*
by W.G. Capy and G. W. Vrinat.
Srconp Parer.— Theory and Production of Oscillations between
Are and Glow.
$1. In the first papert it was shown that in the electric are at
small currents, under certain conditions, the current instead of
remaining constant is subject to pronounced and rapid changes.
These results proved that Lecher’s conclusions regarding the
continuity of the electric are can no longer be accepted without
modification. ,
The method described in the first paper for testing the con-
tinuity of the are discharge consisted essentially in the use of
a bolometer connected in parallel with a self-inductance in the
are circuit. It was found that when the bolometer circuit,
consisting of a Wheatstone bridge with a fine Wollaston wire
of 10 ohms resistance as one arm, was entirely disconnected
from the are circuit, the oalvanometer of the bridge some-
times showed a deflection. As this occurred even when the
two circuits were a meter apart, it was evident that oscillations
ot considerable frequency and intensity must be taking place
in the are.
The study of these oscillations forms the subject matter of
the second and third papers. It will be dealt with under the
following heads:
*This investigation was carried on att the aid of a grant from the
Elizabeth Thompson Science Fund.
+ W. G. Cady and H. D. Arnold, this Journal, clxxiv, p. 383, 1907. Some
months after the appearance of our first paper, Buisson and Fabry (C. R.,
exlvili, p. 1148, 1908) also announced their discovery of the first and
second stages in the iron arc.
Am, Jour. Sc1.—Fourts Series, Vout. XXVIII, No. 164.—Aveust, 1909.
7
90 Cady and Vinal—Llectric Are.
I. Theory of the glow-are oscillations (§§ 2 to 7).
II. Best conditions for the production of the oscillations
($$ 8 to 12). |
III. Experimental evidence of the existence of glow-are
oscillations ($$ 13, 14).
IV. Properties of the oscillations ($$ 15 to 32).
ee anorve
$2. For the sake of clearness the theory which offers the
most satisfactory explanation of the oscillations is set forth
Hie. it
I
here, the experimental evidence in its favor being for the
most part reserved until later.
Let us suppose that we have a circuit consisting of an
electromotive force of several hundred volts, large resistance
capable of fine adjustment, and a short gap between metallic
terminals in free air. Then, as is well known, the discharge ~
will be either in the form of a glow, with a characteristic curve
represented by the line a in fig. 1, or an are, represented
by ed. bc’ is the unstable interval over which the discharge
Cady and Vinal—Electric Are. ant
springs in passing from glow to are, cb’ the interval traversed
in the reverse direction.* The slope of the line dc’ is deter-
mined by E,, the supply electromotive force.
Let the resistance initially be relatively small, so that the
are is stable at d. As the resistance is now increased, there
comes a point where the energy at the cathode is too. small to
maintain vaporization, and the discharge changes suddenly
along cb’ toa glow. The anode may or may not be in a state
of vaporization. Generally the anode ceases to vaporize before
the cathode (“first stage” of our former paper). The oscilla-
tions dealt with here are a purely cathode phenomenon, and
the material of the anode is of no consequence.
If the line cd’ is steep (high impressed electromotive force)
then it may be that the energy expended at the cathode at 0’ is
greater than that at c. If conditions are such that the heat is
largely confined to the neighborhood of the cathode, the tem-
perature of the negative terminal rises rapidly, so that the part
6’b of the characteristic, possibly somewhat modified on account
of high temperature, is automatically traversed, until evapora-
tion sets.in, an are forms along dc’, and the cycle repeats itself
again. The period of this cycle is exceedingly variable,
depending upon a large number of factors, of which the chief
are nature and form of cathode, means of disposing of heat,
distance between electrodes, nature and pressure of gas,
electromotive force and resistance of the circuit, and, as will
be seen, the self-inductance and capacity of the circuit con-
sidered as a system capable of performing electrical oscilla-
tions.
$3. For example, with a supply of 460 volts, using copper
electrodes, free from oxide, one to two mm. in diameter, in free
air, the discharge can be made to pulsate irregularly between
are and glow witha period of from one-half second to several
seconds. On the glow phase the negative mantle covers the
end of the electrode, which becomes incandescent for a con-
siderable distance from its tip before vaporization sets in.
If now the gap is shortened and the current diminished, the
glow will'take place in gas left ionized by the are, and con-
fined in the narrow space between the electrodes. The nega-
tive mantle will occupy approximately the area of the negative
base of the arc, and the temperature of this small area will rise
very rapidly. This hastens vaporization and shortens the glow
phase. Since the energy available for the maintenance of
vaporization on the are phase is now very small, the duration
of the arc is also much reduced. The discharge then pulsates
with a frequency which may reach into the thousands between
the two phases, the temperature of the cathode surface varying
*Cf. Kaufmann, Ann. Phys., ii, p. 162, 1900; also our first paper, p. 395.
92 Cady and Vinal—Electric Are.
between the boiling point of the material and one very
slightly below it. This local heating is now largely dependent
on the condition of the cathode surface, and the period will
fluctuate as the discharge wanders from point to point over
this surface. The oscillations which we recorded photograph-
ically, using copper electrodes in air, are to be regarded as an
instance of this sort (S 9).
$4. In order further to increase the rapidity of the pulsa-
tions, attention must be paid to the surrounding gas. As will
be seen (§ 10), when a suitable gas is chosen, the current
reduced to the right extent, and the distance ‘between elec-
trodes made very small, the period of the pulsations is deter-
mined chiefly by the electrical constants of the circuit. In
other words, high-frequency electrical oscillations. take place,
governed by the resistance, self-inductance, and capacity, con-
centrated. or distributed, of the are circuit, which react upon
the discharge, and control its periodicity. The discharge then
imparts energy to the oscillations as the escapement of a clock
imparts energy to the pendulum. The material of the cathode
may affect the intensity and permanency of the oscillations,
but not their frequency.
In this respect the glow-are discharge is analogous to the
spark-gap, except that it seems to consist of undamped oscilla-
tions ($29). It is also analogous to the oscillating are
of the Thomson-Duddell type, whose period of oscillation
depends essentially on the capacity and self-inductance in
parallel with it. The distributed self-inductance and capacity
of the glow-are discharge circuit itself correspond to the self-
inductance and capacity in parallel with the Duddell are, and
the steep slope of the line dc’ (fig. 1) to the “falling” charac-
teristic of Duddell.
High-frequency oscillations of the Duddell type, in which
the only self-inductance and capacity were those of the elec-
trodes and adjacent parts of the circuit, have been described
by Stschodro* and Simont, but in each of these cases a stable
are of the ordinary sort seems to have been used.
§ 5. During the passage of the oscillations the discharge
circuit itself behaves like an open oscillator, radiating energy.
Thus it is possible to obtain energy from the dischar ge in either
one of two ways, viz.: by coupling a coil in the circuit indue- -
tively with a secondary coil outside, or by making use of the
electromagnetic waves radiated from the’ various parts of the
circuit. The former method was used in our frequency
determinations. The radiations will be considered in § 32. |
* Stschodro, Ann. Phys., xxvii, p. 225, 1908.
+ Simon, Phys. Zeitschr., ix, p. 872, 1908.
Cudy and Vinal—Electric Arc. 93
$ 6. The net result of the glow-are pulsations is the trans-
formation of a portion of the direct current energy into that
of an alternating current, giving rise to an alternating current
superposed upon the direct current. In this respect the dis-
charge behaves like a microphone contact, or like a current
interrupter. Such cases may be treated either as pulsating
resistances or as alternating electromotive forces.* Suppose,
for example, that a constant electromotive-force # sends a
current / through a circuit of self-inductance Z, constant
resistance /’, and pulsating resistance aft cos pt. Then
Jie § + IR (1 + acos pt).
This case is discussed by Barkhausen (I. ¢.), who by a pro-
cess of successive approximations arrives at the conclusion that
the enrrent wave is of a form represented by a fundamental
vibration with a system of higher harmonics. The equation
has been exactly solved for another purpose by Mr. L. Cohen,
to whom the writers are indebted for his kind permission to
make use of the solution. In a paper shortly to be published
by Mr. Cohen it will be shown that
T= = oe a
TR) /aR ap)
cos (pt — $)—
fita’ cos (2 pt — ¥,— ¥,) on
ON Ce ere) (ee psy
where ¢, W,, y,, are constants. |
For the present purpose the most noteworthy feature about
this solution, beside the existence of the harmonic terms, is the
fact that the greater the value of @, that is, the greater the ampli-
tude of the variable resistance, the more slowly does the series
converge. This helps account for the intensity of the higher
harmonics that are recorded below (§ 25). The equation just
quoted fails to take into account two facts: first, that the
capacity of the circuit plays an important part in the case of
oscillations of high frequency, and second, that the resistance
of the electric discharge does not pulsate sinusoidally, but in
a much more complex manner.
§$ 7. Of the relative durations of the are and glow phases
we know little, but the shorter one of these is in relation to the
other, the more pronounced must the harmonic terms become.
In any event the presence of a complex wave form, involving
*Barkhausen, Das Problem der Schwingungserzeugung, Leipzig, 1907,
pe 19:
94 Cady and Vinal—EKlectric Are.
a large family of harmonics, may confidently he predicted.
Owing to the lack of symmetry between are and glow phases,
both odd and even harmonies may occur (§ 25).
A further complication arises from the fact that since the
oscillations adapt their frequency to the natural period of that
part of the circuit which they are able to penetrate, a kind of
resonance sets in, with the result that the effective value of the
alternating current may be greater than that of the direct
current supplied by the generator.
This shows that fora certain time during each cycle the
direction of the current is reversed. It is evident that in order
Fie. 2
for this to take place the capacity. of the are circuit must play
an important role. In this respect the oscillations have a
slight similarity with the third type of oscillation studied by
Blondel in the singing are.*
The form of the current wave must be somewhat as repre-
sented in fig. 2, Here the full lnes represent the normal
current pulsating between arc and glow where the effects of
resonance are neglected. The beoled lines show the form of
the current curve when the pulsations take place in synehro-
nism with the natural period of the circuit. The current on
the arc phase rises much higher than before, while the glow
phase with the current in the positive direction practically
disappears, a brief discharge in the opposite direction taking
its place.
If the frequency were lower, the potential difference would
have to rise very high in or der to re-start the discharge at each
reversal, and the result would be practically a succession of
sparks. But in view of the high frequency (on the order of
a quarter of a million) and of the short distance between the
* Blondel, l’Kcl. Elect., xliv, p. 81, 1905
Cady and Vinal—FHlectric Are. 95
electrodes, it is clear that the glow phase can begin promptly
after each reversal of current.
The frequency is too inconstant to permit of an analysis of
the wave form by any of the ordinary types of oscillograph.
On the other hand, an estimate of the frequency on theoretical
grounds would require a knowledge of the resistance, self-
inductance and capacity not only of the circuit, but of the
discharge itself. To compute these factors would be difficult,
involving as it must an exact knowledge of the extent to
which the oscillations penetrate into the circuit.
Il. PropucTrion AND APPEARANCE OF OSCILLATIONS.
§ 8. The oscillations when strong were detected by means of
a bolometer insulated from the are cireuit and 10 to 100™
distant from it. In this case the greater part of the energy
received by the bolometer circuit was in the form of electro-
magnetic radiations from the nearest portions of the discharge
cireuit. With feeble oscillations like those first described
below, it was necessary to connect one point of the bolometer
circuit with one terminal of the arc.
Eyidenees of feeble oscillations were obtained with a copper
are in free air, and with iron and silver arcs in nitrogen. (First
paper, pp. 391, 410.) In some of these cases the cathode was
also of carbon.
Further study of the copper arc in air has yielded the fol-
lowing results, obtained in general with an e.m.f. of over 400
volts.
For oscillations the copper cathode must be clean and free
from oxide. ‘This is in conformity with our earlier observa-
tion that no glow discharge is possible from an oxidized
electrode. The oscillations can sometimes be detected by the
bolometer when the current is as large as one ampere, and
they reach their maximum intensity at 0°2 or 0°3 amp. The
length of arc may be as large as 2"™, but best results are
obtained with a very y short gap between the electrodes.
. Water-cooled electrodes do not offer an appreciable advan-
tage over those at high temperature. Ample evidence shows
that the change from first to second stage at the copper anode
has nothing to do with the effect, which is purely a cathode
phenomenon. Like effects are produced whether the anode is
of copper or carbon.
The beginning of strong oscillations is indicated by the
appearance of the discharge, which assumes an aspect inter-
- mediate between that of an are and of a glow. A very charac-
teristic tinkling sound is heard and the needle of thé voltmeter
connected across the discharge trembles violently and irregu-
larly between two extreme positions.
96 Cady and Vinal—Electric Are.
Fig. 3 represents the characteristic curve of the copper are
in air. The line marked with crosses was obtained when no
oscillations were present, probably owing to a.trace of oxide on
the cathode. The heavy line shows the effects of oscillations,
which began in this case at about 0-4 amp. The limits of the
shaded area indicate roughly the extreme swings of the volt-
meter needle, whose inertia undoubtedly prevented it from
reaching the actual extremes of potential, particularly on the
glow phase, the duration of which is very short.
Above 0-4 amp. the discharge is a stable are. At 0-4 amp.
the pulsations between arc and glow begin, feebly at first, but
imcreasing in intensity as the current decreases. With a higher
supply e.m.f. it would doubtless have been possible by further
Teh, 3}.
Pee ees
NS
ala) se
Ss
reducing the current to observe the gradual diminution in
intensity until a steady glow was reached. Under whatever
conditions the oscillations are obtained they are always of
maximum intensity at a certain current. |
§ 9. In order to throw light on the nature and frequency of
these oscillations the image of the are was allowed to fall on a
rapidly moving photographic plate. An are between a carbon -
anode and copper cathode in free air was used, the electrodes
being horizontal. The photographic plate was allowed to drop
through a vertical wooden chute, its motion being accelerated
Cady and Vinal—Electric Are. 97
by means of rubber bands until it passed an opening in the
chute at a velocity of about 565cem. / sec. = 0:000177 sec. / mm.
By means of an achromatic lens a minute image of the are was
formed on the plate as it passed this opening.
A number of plates were dropped under varying conditions
of arc, the current being on the order of 0°3 amp. and the
length of arewls™:
In nearly all cases where the bolometer system showed a
deflection the record on the photographic plate was not a con-
tinuous line, but broken into a system of more or less periodic
dots or dashes. These occurred in trains of from five to °
several hundred waves, the period being practically constant
throughout each train, but varying abruptly from one train to
the next. No evidence of damping could be seen.
The lowest frequency observed was about 1,300 per second,
the highest about 43,000. In one case a change from a
frequency of 1,300 to one of 10,000 took place on the same
record. The velocity of the plates and clearness of the image
hardly permitted the identification of a frequency higher than
50,000, so it cannot be affirmed that higher frequencies were
not present.
These experiments show that in the oscillating carbon-
copper are in free air, the current and the light emitted from
the are are varying constantly with a period which itself is
subject to sudden and great variations (cf. § 3).
§ 10. Following is a brief account of experiments made
with a view to learning under what conditions the regularity,
frequency and intensity of these oscillations can be increased.
In CO, and in N. Deflections of bolometer small and
unsatisfactory.
In H. No arc, but only a glow, could be obtained except
when the current was over 0°3 amp.
A little benzine vapor was then introduced by allowing the
hydrogen to bubble through a bottle of benzine.* This
enabled us to decrease the are current to 0°2amp., at which
current good oscillations occurred. However the use of ben-
zine was discontinued owing to the copious deposits of soot
and to the tendency of the arc to go out.
In iluminating gas. ‘This gave far better results than any
of the gases mentioned above. A silver cathode was chiefly
used. On account of the deposit of carbon dust from the
dissociated gas, the latter was diluted by the addition of a cer-
tain amount of nitrogen or air. It was in illuminating gas
that large deflections were observed for the first time when the
bolometer circuit was entirely disconnected from the are
* Cf. Barreca, Electrician, Jan. 17, 1908.
98 Cady and Vinal—Kiectric Arc.
circuit. The effect was decidedly better at atmospheric pres-
sure than at any reduced pressure. No oscillations, however,
could be detected when the are was surrounded by the flame
of a Bunsen burner.
in H and acetone vapor. The tests with benzine vapor and
with illuminating gas indicated that the presence of hydro-
carbons around the are greatly facilitates the production of
oscillations. In the attempt to find a carbon compound that
should give rise to less carbon dust, we tried a mixture of
hydrogen and acetone, as described by Fischer.* This was
produced by passing the hydrogen from a Kipp generator
through the upper part of a bottle containing acetone. It
was found better not to let the hydrogen bubble through the
liquid. In this manner enough acetone vapor was present to
permit of strong oscillations without causing a very rapid accu-
mulation of carbon dust. Nevertheless it was necessary to clean
the electrodes frequently, and at no time were the oscillations
comparable in constancy with those from the spark or Duddell
are. Using the most careful precautions, we could not keep
the oscillations from being fickle and irregular. Hardly ever
could a resonance curve be obtained without the necessity of
bringing the electrodes together, rotating one of them, or other-
wise changing the character of the oscillations. Hence the
values of frequency given below can be considered only as
rough approximations. Nearly all the observations to be
described were obtained with the discharge in hydrogen and
acetone.
The frequency in illuminating gas or acetone is much greater
than in air. The carbon compounds around the discharge seem
to make the cathode base, on the glow phase, more concen-
trated, and thus to accelerate its rise in temperature. The
discharge is steadier and more quiet than im air, and the
frequency is comparatively constant, being determined by the
electrical constants of the cireuit (cf. § 4).
S11. Tests with Different Metals. Any metal, or carbon,
may serve as anode, though when carbon is used the produc-
tion of soot is annoying. As cathode we have tried Pt, Fe,
Ae, Cu, Al, Pb, and sott solders all -oiverinitial oscillations
of appar ently the same intensity and frequency, though altera-
tion of the surface of some of these soon destroys the effect.
No difference in frequency could with certainty be detected
whether the cathode was of Ag, Cu or Al. A fine copper wire
produced the same effect as a large disc. With carbon as
cathode only the feeblest pecalleone could be observed—
though it was with this arrangement that the oscillations were
* Fischer, Ann. Phys., xxviii, p. 57, 1909.
Cady and Vinal—Electric Are. 99
first discovered. Black oxide of iron, Fe,O,, gave feeble
oscillations.
$12. When the e.m.f. of the supply was gradually reduced,
the oscillations became less intense, and a larger current was
found necessary. With a supply of only 145 volts a very
feeble deflection of the bolometer was still perceived, the
discharge current being 0°8 amp. ‘This deflection may have
been due to mere irregularities in the burning of the are. At
any rate, there seemed to be no critical discharge potential at
which oscillations suddenly began.
lil. Experimenta EvipENcE oF GLow-ARC OSCILLATIONS.
$13. That a gradual transition can be observed from a
visible slow change between are and glow in air, through the
more rapid pulsating discharge recorded by photography, to
the high-frequency oscillations in hydrogen and acetone, is
a priori evidence that in these last oscillations the change
between are and glow is still taking place. The alternative
hypothesis, that of an intermittent spark discharge, is, of
course, obvious, and indeed it may be that a evadual transition
from glow-are pulsations to a pure spark discharge, by raising
the e.m.f. and at the same time decreasing the current, could
be accomplished. That the present phenomenon is nota spark
discharge in the ordinary sense is rendered probable by the
small damping of the oscillations (§29). Moreover, if this were
a spark discharge, the train of waves that constituted each
spark dying down nearly to zero before the next discharge
passed, then in order to explain the observed fact that the
effective total current is several times as large as the mean
direct current, we should have to assume a very large initial
amplitude. But this would be hard to reconcile with the
relatively low impressed e.m.f.
$14. According to the explanation of the oscillations here
advanced, the potential drop across the discharge must rise to
that characteristic of a glow-discharge once during each period.
It was determined to test this, and at the same time to answer
the question as to whether the oscillations might be due to a
rapid succession of short sparks. For in the latter case, the
potential difference wonld be expected to rise considerably
above that of a glow discharge.
Considering the high frequency of the oscillations, the only
available method for measuring the maximum potential differ-
ence seemed to be to connect across the discharge a calibrated
spark-gap. That this method is applicable even when the
frequency is as high as one million follows from the work
100 Cady and Vinal—FElectrice Are.
of Voege* and Algermissen,} especially as the latter writer
shows that for short spark lengths the high-frequency dis-
charge potential differs but little from the static potential.
The spark-gap used consisted of a brass plate A (fig. 4) 1™
in diameter, which served as anode, and as cathode a small
steel sewing needle &. These electrodes were mounted about
1™™ apart in a small glass tube, and were sealed in with
sealing-wax. A side arm C@ from the tube communicated
with a hydrogen generator, air-pump, and manometer. The
copper are in a mixture of hydrogen and illuminating-gas at
Ning ae
atmospheric pressure was employed as the source of oscilla-
tions. Short, thick wires connected the arc terminals with the
spark-gap.
Great difficulty was at first experienced in causing a spark
to pass promptly at sufficiently low potential. An iron are,
and later a powerful spark between zine electrodes, placed
close to the glass tube, did not materially help matters, nor did
ionizing the gas in the tube directly by running the discharge
from a small induction-coil from point to plate just before
each observation.
It then occurred to us to keep the gas artificially in a state
of ionization while the sparking potential was being ‘applied.
To this end two platinum wires /), /’ were sealed into the
tube on opposite sides of the spark-gap, about 5™" in front of
the brass disc. The terminal A was kept constantly connected
to the positive terminals of the are and of a variable e.m.t.
for calibrating. 6 could be connected in rapid succession to
the negative terminal of the calibrating e.m.f. (through a high
resistance), and to the cathode of the are. Observations were
carried out thus: the gas in the tube was exhausted to a cer-
tain pressure, the auxiliary discharge from a small induction
coil started between D and /, and the lowest static potential
observed that just sufficed to start a discharge between
Aand B. £& was then quickly connected to the cathode of —
the are, and it was noted whether or not a discharge between
A and B took place. The discharge between D and i was
* Voege, Elektrot. Zschr., xxv, p. 1033, 1904.
+ Algermissen, Ann. Phys., xix, p. 1016, 1906.
-Cady and Vinal— Electric Are. 101
maintained throughout this operation. Then the pressure in
the tube was varied and the observations repeated. Each
variation of gas pressure of course changed the minimum
sparking potential, so that after a series of such observations it
was possible to set a sufticiently close upper limit for the
maximum potential drop across the arc.
The lowest discharge potential observed in this way from
the calibrating circuit was 340 volts, the gas pressure in the
spark tube being about 7". With a 460 volt supply e.m-t.
for the arc, the maximum potential drop across the arc when
oscillations were present was always found to be at least 340,
usually about 385, but never higher than 397 volts.
These values are hardly greater than what would be
expected for the drop across the terminals of a short glow dis-
charge, where the greater part of the total drop is that at the
cathode. Hence, in so far as the spark-gap method is permis-
sible in the case of high-frequency oscillations, it seems proven
that the discharge is not intermittent and discontinuous, but
consists of an exceedingly rapid change back and forth between
are and glow.
The use of auxiliary ionizing electrodes is in every way to
be recommended for work of this sort. By their aid, the
response of the tube to an applied voltage above the minimum
is Instantaneous, while the minimum discharge potential itself
is sharply defined and well reproducible. The presence of the
auxiliary ionizing discharge did not seem to make the critical
discharge potential lower than it was after the usual lag with
no artificial ionization.
SUMMARY.
I. The theory of a type of pulsating discharge, called for
convenience the “glow-are” discharge, is explained. This is a
spontaneous and rapid change back and forth between are and
glow, whose essential feature is that the rate of expenditure of
energy at the cathode on the glow phase is greater than that
on the are phase. Under suitable conditions the fr equency of
these oscillations is so great that they take place in synchronism
with the natura] period of the neighboring portion of the dis-
charge circuit, as determined by its resistance, self-inductance,
and capacity, distributed or concentrated. An - oscillating
current is thus generated, whose intensity may be greater than
that of the supply current, It is shown that higher harmonics
must be prominent in the current wave.
Il. The conditions for best oscillations were investigated.
The copper are in air gives pulsations slow enough to be
recorded on a photographic plate, but the oscillations are most
102 Cady and Vinal-—Electric Are.
rapid and powerful when the discharge takes place in a mix-
ture of hydrogen and acetone vapor.
III. Strong evidence in favor of the glow-are hypothesis is
derived from the measurement of the maximum potential dif-
ference assumed by the discharge during each eycle. By
means of-a calibrated spark-gap it was found that this maximum
does not rise above that characteristic of a glow discharge. A
new method was employed for keeping the gas in the neigh-
borhood of the spark-gap in a state of ionization.
Scott Laboratory of Physics,
Wesleyan University,
June 3, 1909.
[To be continued. |
Mixter— Formation of Trisodium Orthophosphate, etc. 108
Arr. XII.—The Heat of Formation of Trisodiwm Ortho.
phosphate, Trisodium Orthoarsenate, the Oxides of Anti-
mony, Bismuth Trioxide ; and fourth paper on the Heat
of Combination of Acidic Ovides with Sodium Oxide; by
W. G. Mixter.
[Contributions from the Sheffield Chemical Laboratory of Yale University. |
Tue heat of combination of an acidic oxide with sodium
oxide may be derived from the heat of formation of the anhy-
drous salt, and, conversely, the thermal effect of the union of
the elements in a salt may be calculated from the heat of com-
bination of the oxides forming it. Only the latter method is
applicable to insoluble salts of weak acids, as, for example,
sodium antimonate. The investigation includes new determi-
nations of some constants and the results obtained agree with
those of other investigators and show the value of the sodium-
peroxide method.
Kilogram-calories, which are indicated by the decimal point,
are used in some of the calculations for sake of brevity. The
gram-calorie is, however, more philosophical, as the gram is
the unit of mass in physical science and quantities in chemis-
try are commonly expressed in grams. Unless otherwise indi-
eated, the constants used in the calculations are Thomsen’s and
are taken from his Thermochemistry, the English translation
by Katharine A. Burk.
Trisodium Orthophosphate.
The red phosphorus for the work was digested. with hot
dilute nitric acid, next with a concentrated solution of sodium
hydroxide and then washed and dried. When exposed to
moist air for twenty-four hours, it gained in weight 0°16 per
cent. The following are the experimental data:
1 2
PesacwilOrus. 9. 4022 op shee ke 1000 gram 1:000 gram
Sodium peroxide _---.-- ae a re 13 a
Water equivalent of system __-- 4,136 oF 3,999 a
Temperature interva]l._....__-- 1:986° 2°004°
Mean OUSELVed 08 222. 22h. 22: 8.214° 8,014°
A OL. Oxidation of ikon |... — 48° —48°
For 1 gram of phosphorus...-- 8, 166° 7,966°
In the first experiment the mixture was in a silver cup the
rim of which only was in contact with the cold sides of the
bomb. With this arrangement the fusion cools slowly and
104 Miater—Formation of Trisodium Orthophosphate, ete.
the reaction is more complete than without the inner cup, as
was the case in the second experiment. Using the first result
we have
5Na,O, + 2P (8166 x 62) = 3Na,O,P,O, + 2Na,O + 506,292°
5Na,O. +) BO ==) SINaiO © pgp ae a aye eee 97,000°%
3Na,O qe GP ab 50) ss "3Na,0,P,0, oo Sl eae gies
DP ee. P2Qt oes SUES ek Ss ee eee 369,900°
3Na,O + P.O. = "3 NVOOr © 4 ee ee 230, 300m
In the Physikalisch-Chemischen Tabellen with reference to
Berthelott 3Na,P,4O0 = 452°4°, from which is derived 235°5°
for the heat effect of Na,O+P,0,. Berthelott and Thomsen
both found the heat of neutralization of phosphoric acid by
sodium hydroxide to be 34:0. From this we derive Na,P,O,,-
Aq = 469°5°. Joly§ gives the following: Na,PO, 24HO =
—14°5° and Na,PO,+24HO =+ 481%. (O=8.) The heat of
solution of Na,PO, is the sum of these numbers, 1. e., 33°6°.
The experimental data are not given and the writer does not
understand the result, which is apparently twice too high.
Subtracting one-half of it, 16°8°, from 469°5° we have Na,,P,O,
= 452-7°, which is essentially the same as given in the Physi-
kalisch-Chensischen Tabellen, as stated above.
From the result of experiment 1 we have
3Na,0*% 4 2P +50)" 2Na PO, ae eee 603°3°
6Na + 30° = 3Na,07+ (09-8 X13) 4. Sie 12907
2(8Na. +-°Po+4. 40) = 2. 2e222 2 eer
SNA tee Pac 4 Oe oie ea) pian BL LN oe ee ee
The heat of formation of sodium phosphate found by the
two methods is 452°7° and 451°4°, and hence the heat of combi-
nation of sodium oxide with phosphorus pentoxide obtained
by the different methods is, essentially, the same.
Trisodium Orthoarsenate.
The arsenic for the following experiments was sublimed and
then heated in a current of dry hydrogen in order to remove
any oxide present.
if 2 3
PALTSETIUC) de ote ts Seta ae 5000 gr. 5:000 gr. 6°000 gr,
SOCIAL (EOP NO Ya ak ee 23 Bae de® Dao 210, os
Water equivalent of system 4,028 . “3,945 - ‘3,994 i
Temperature interval ._--.. 2EOGM « 2°865° 3°247°
* De Forcrand, C. R., exxvii, 514.
+ Ann. Ch. Phys. 6), ibe Per
t Loc. cit. §C. R., civ, 1704.
Mixter— Formation of Trisodium Orthophosphate, ete. 105
eac observed: : 20.00.0022 2 10, 748° 11,309°¢ 12,969°
©) OF. oxidation of iron. -. —48° —A4s° —48°
pen Oxy oem, absorbed :_ —58° — 90° = 5°
10,637° 11,171° 12,85 4°
Hor lt cram of arsenic... _- - pats 2,234° SLB De
The mean of the results is 2,168° and for 150 grams of arsenic
it is 825°2°. The heat of combination of sodium oxide with
arsenic pentoxide is derived thus:
oNaO + 2As — 3Na,O, As,O, +. 2Na,0 +4 2212-22. 1825-2
Ome OO — Na Oot oo ee 97-0
eee 2 As. 5O == 3Na,O, AsO, + 22-222 4.2- 2 422-2
Be) eat NSO sok Gs Se ee oe fee pa ee 219°4
3Na,0 + As,O, = 3Na,0, AS, OF Ee OR eo sare nine went ROO S
Two determinations of the heat of union of arsenic pentox-
ide with sodium oxide gave for 1 gram of the former 792° and
867° respectively. ‘The combustions were not satisfactory, as a
little sodium arsenite was formed. Using the higher result, we
have 867 X 230 = 194,400° for the heat effect of 3Na, O+As 1On
The heat of formation of trisodium orthoarsenate is derived
as follows:
meen 1 Ae -—5 0 > 9Na AsO, +o. eb ose ee 42929
MO. OND On i. aoe ek 299-4
PE eed ee ee Ee Ba ys ee TO Ge
Eee oe pie a ae ee ON ae BO OF Re
The heat of formation of trisodium arsenate in solution eal-
eulated from. Thomsen’s heat of neutralization of arsenic acid
is 381°3; subtracting 17-7, the heat of solution of Na,AsO,
(Joly),* gives 363°6 for Na,,As,O,.
Antimony.
A mixture of pulverized antimony and sodium peroxide
does not burn throughout the mass when kindled at one point,
hence sulphur or some other substance must be added to the
mixture to furnish the heat required to effect the combustion.
The following are the experiments:
a
PRPERIMLOUY 2 ee St coe os 2 ee ee 10°000 grams 10°000 grams
“5 TLTUEE (0 i plc Sea eae AO 0). St 1:000
Boamim peraxide. —.... 2s: 3-2 31 ee 30 e
Water equivalent of system... 4,028 6 4,222
Temperature interval -.22--.- 4°384° 4°208°
* ©. R., civ, 1704.
Am. Jour Sci.—FourtH Series, Vout. XXVIII, No. 164.—Aveust, 1909.
8
106 Mixter—Formation of Trisodium Orthophosphate, ete.
Heatobserved alu. 2. le. ike LL 6Ctls 17, 766°
“ of oxidation of sulphur.-—5,271° —5,271°
ce 6¢ ce (74 iron a aie == 4 SIE —48°
<< -* oxygen absorbed -_--. - — 60° — 72°
12,281° 12,375°
The mean result for 240°4 grams of antimony is 296, 300°.
As an excess of sodium oxide was present in the fusions
Na,SbO, must have been formed, hence we have
5Na,O, + 285b + 2Na,SbO, + 2Na,O -— 222528 296,300°
BIND OBO OU cass ge ae eee eee ee 97,000°
3NaO- +: 28b + - 5OR== 2 Na SbO ne es eee 393,300°
Antimony Pentoxide.
The preparation of the pentoxide was made as follows:
antimony was completely oxidized by prolonged digestion with
hot concentrated nitric acid, and the antimonie acid obtained
was washed to remove soluble impurities. It was converted
into oxide by heating in an electric furnace until the weight
remained constant at about 400°. The product was allowed to
cool in a closed tube, as antimony pentoxide absorbs water
from the air. It was free from a lower oxide and 1°7662
orams yielded 1°6784 grams of Sb,O,, which is equivalent to
1:7662 grams of Sb,O,. For the following experiments anti-
mony pentoxide was weighed in a stoppered bottle and mixed
with the sulphur and sodium peroxide in a closed bomb.
3 + 5
Antimony pentoxide_----- 10:059 or. 10°007 or. TOré%aser-
SoG ola tae eg a eee ia 27000. <4 2:000)%: 27000."
Podium: peroxides ae =e. u 21 me See 21S) Stic
Water equivalent of system 4,100 “4.028 ARE &¢
Temperature interval. ---- 3°789° 3°834° 3°900°
Heatvobservedie =a Kapoaoe 15,444° hegaon
‘** of oxidation of sulphur —10,542° —10,542° —10,542°
6¢ 6¢ «6 66 ir One eAeXe — Age LASS
< -soxyoen evolved =2 +151° + 359°
5,096° 4,854° 5,502°
Mor loram,ot- sb. O-es22 es 507° 485° 515°
The result of 4 should not be included in the final value as
the oxygen evolved was lost. The mean of the other two is
511 and for 320°4 grams it is 163,700°.
Antimony Trioxide.
Antimony trioxide was made by treating the trichioride with
dilute ammonia, washing the product thoroughly and then
Mixter— Formation of Trisodium Orthophosphate, etc. 107
heating it out of contact with air as long as water came off. It
was free from a higher oxide.
The experimental data are as follows:
6 7 8
Antimony trioxide-.----- 9°985 gr. 10°318 gr. 8994 er.
2 _ CUS aaa 27000 “ L800; < 2°200 *
podium peroxide___-.-.-- 28 ee 2D as 28
Water equivalent of system 4,110 “4,097 “© 4,182 cs
Temperature interval - ---- 4°190° 4:008° 4°209°
hheagooserved,-..- =... Li. 2205 16,417° 17,602°¢
“ of oxidation of sulphur —10,542° —9,488° —11,596°
66 “¢ ce ce iron ate == AIR == Ege —48¢
6,631° 6,881° 5,958°
Miata Oras 222 S225 l 2. 664° 667° 662°
The oxygen absorbed or evolved in each of the combustions
was insignificant. Different mixtures were taken in order to
learn whether or not the thermal result is influenced by the |
proportions of antimony trioxide, sulphur and sodium peroxide.
The fact that the results are the same indicates that the same
sodium antimonate was formed in each instance.
The mean of the experiments is 664 and for one gram mole-
cule of antimony trioxide it is 191,500°.
Antimony Tetrowide.
Antimony tetroxide was made by heating antimonic acid in
an electric furnace until the product did not lose weight at a
dull red heat. In the following experiments the absorption of
oxygen was insignificant :
9 10
Antimony tetroxide -__.-_-- 10°233 grams 7°386 grams
SL UU es eee ee 2-000 2-000'%
podium peroxide... .-.2.-- 23 g 22 oo
Water equivalent of system-_ 4,16) ee 4,180 Gc
Temperature interval___-~.-- 3°8 (le 3°486°
Bieat-opserved |=. 2 16,107° WAS ks
‘“* of oxidation of sulphur. —10,542° —10,542°
““ 66 “¢ 6¢ iron pet te S=AR° SARS
5,517° 3,981°
OR TAT es 0 Ss IN 539° 539°
The result for 304-4 grams of antimony tetroxide is 164,100°.
In all of. the combustions of antimony and its oxides the
oxidation was complete and no antimonite was formed. The
108 Miater—Formation of Trisodium Orthophosphate, ete.
solutions of the fusions were tested adding silver nitrate and
then ammonia. No black substance remained, proving that an.
antimonite was not present. The insoluble residues from the
fusions when treated with a boiling solution of potassium
hydroxide, silver nitrate and ammonia also yielded no black
substance. The insoluble residues mentioned even after long
digestion with water reacted alkaline, showing that the
hydrolysis of the sodium antimonate was not complete.
The heat of formation of the oxides of antimony is derived
from the experimental results as follows :
3Na,0\498b 4150 == 2NaSbO)- a ee 393-3
3Na.0-4+) Sb,0- = 2Na SbOl 20 ela
OSs 00: = SiO ea eee te 2 229°6
9Na.O, + Na,O +°Sb,0, = 2Na,SbO, 4 . 2.2.22 aigmes
QNia. Or 2Oo=: WNa OW ah o5 eee ee aie ee 38°8
3Na,O; -- 8b,0, .+. 20. — 2NaSbO) 4 ee 230°3
3Nia,O:-4+..Sb,O) = g2Na SbOye 32s 52 eee ee 163-7
Sb:0; + 20 = Sb205 + Sa ee mee See ye 66-6
Na_O; +" 9Na Ov fe Sb, 0) = 2Na SbO 3 ee 164°1
Na,O + Oe s UNGO. Ea OE ee ee 19°4
3Na,0 + :S8b,0, + O° = 2Na SbO, io ee 183°5
3Na,O) 4 28b.07> = 2NaSbOk a: se! eh 163°7
SbhoOs 42°0 = ShoOs" 4 2 ee 19°8
9Sb EO = SiO seal ee S heee t ee 229°6
SiO. + 60 tee BDO os ee ee 19°8
28br 3 140) = SbeOwe se ae oie Ve rc as i 209°8
ISb 1b O A=" Sb Ow ts a en) a 229°
Sb.0, 4°20 =°Sb,0 4. ue
28b.24, 30.'= “Sbi0s. 42. oe are oe 163-0
Thomsen derived the heat of formation of antimonic acid
from that of the pentachloride and the heat effect of the hydro-
lysis of it and obtained Sb,, O,, 3H,O = 228°8°, the writer
found that Sb,, O, = 229°6°. The difference. between these
two numbers is within the limits of error. Thomsen stated —
that the antimonic acid was free from chlorine and the writer
has also found that the hydrolysis of antimony pentachloride is
complete. Evidently the heat effect Sb,O,, 3H,O is quite
Miater—formation of Trisodium Orthophosphate, etc. 109
small, as might be expected, since As,O,, 3H,O=6°5* only, while
fo) oe. OF = 30°C".
In conelusion it may be stated that the heat of formation of
trisodium antimonate from its elements is 346°4°, and is derived
as follows:
ERO 25h) = 50) .—. 9Na ShO. bo eo ee) 393°3°
Seine en ONG ©) Ss i ee ee 299°4°
Ne 25h 80 = INaSbO, + -..-..2..-.--. Geno t”
ete 25D AQ — Na SbO, - +... -- ae ee ces -2 es 346°4°
Bismuth Trioxide.
Pulverized bismuth was burned in experiment 1. The tri-
oxide was made by heating pure basic bismuth nitrate in a
combustion tube to dull redness until acid fumes ceased to
come off. A weighed portion of the oxide was found not to
lose weight after fusion. The following are the experiments :
i . 3
armament eS ts 20°000 er.
eeunOUrned — ... 2 O99 ame
peered = 19:005: “
eee EO NMULOs 25-00 2 2 20°000 gr. 20°000 gr.
pepe ee 1000" 2-00" 1+ 2-000) &
Water equivalent of system 8,935 “4-256 “ 4.005 sf
Temperature interval _- ..-- 3°347° 3°445° 3°642°
Piece onserved = = ..-...... 13;170° 14,662° 14,586°
‘“* of oxidation of sulphur —5,271° —10,542° —10,542°
ce 66 <4 66 iron .. e —— 4g Ae —48°¢
foo Oxyoen set.free _... . —60° —28° — 48°
7,791° 4,044° 3,948°
ee orrany ok a ' 410° 202 197°
In calculating the heat of formation of bismuth trioxide it
makes no difference what sodium salt is formed in the fusion
since the same one results from the action of sodium peroxide
on both metallic bismuth and its trioxide. Moreover, assum-
ing that a different peroxide is formed than Bi,O, does not
change the final result, since the heat effect of Na,O+O would
vary by 19,400° in both of the calculations below. From the
mean of experiments 2 and 3 we have
nO ema OO. bt O=2(NaO)x bi OF +). 122.2 92°8°
2Na a i 2Na,O, fi reli oh i gi eae ean 38°8
xNa,O + Bi,O, + 20 = (Na,O)xBi,O, + ----.-.--- 131-6°
110) Mixter—FHormation of Trisodium Orthophosphate, ete.
From experiment 1 we have
5Na.0.- - 2Bi = (Na,O)xBi,0. + xNa,O >. .2 oe 170°6
INO BO = SN a0 Se. oe er ee eee 97°0
xNaO + '2Bi 4+ 50>=. (Na,O)xBO) 4 eee — 267°6
The heat of formation of Bi,O, is 267°6° — 131°6° = 136-0.
This agrees well with Ditte and Metzner’s* result of 137°8°.
The fusions of the calorimetric experiments left when
treated with water a dull yellow product, which after drying
Fig. 1.
320}
26
24
/60
fd As Sé Bi
at 100° contamed a peroxide of bismuth, water and a little
sodium. It yielded on heating about half the weight of oxy-
gen required to convert the Bi,O, left into bi,O,, that is, only
about one-half of the bismuth in the substance was in bis-
muthie acid. Several preparations were made by heating a
mixture of bismuth trioxide and sodium peroxide, and it was
found that the bismuth compound formed gave off oxygen
=CLR., exv, 1303.
Mixter—Formation of Trisodium Orthophosphate, ete. 111
4 |
slowly at room temperature and rapidly in hot water, retaining,
however, considerable peroxide.
In the figure, atomic weights are plotted as abscissas and
heats of combinations as ordinates. The line I shows the heat
of the reaction 3Na,O, R,O,; II of R,, O,, and III of+K,, O,,.
We observe that, as the atomic weight of arsenic is nearly
the mean of the atomic weights of phosphorus and antimony,
so the heat of combination of arsenic pentoxide with sodium
oxide is almost the mean of that of the union of phosphorus
pentoxide and antimony pentoxide. The heat effect of 3Na,O,
R,O, is, therefore, closely related to the atomic weights of
phosphorus, arsenic and antimony, and not to the affinity of
these elements for oxygen. We also observe that the heat of
oxidation of arsenic trioxide is nearly the same as that of anti-
mony trioxide to the pentoxide.
112 Browning and Fint— Tellurium Dioxide.
Art. XIII.—The Quantitative Precipitation of Telluriwm
Dioxide and its Application to the Separation of Tellu-
rium from Selenium; by Putte EK. Brownine and W1It-
LIAM R. Friinr.
[Contributions from the Kent Chemical Laboratory of Yale Univ.—cci. ]
Aut those processes for the estimation of tellurium in which
the tellurium is precipitated and weighed in elementary con-
dition are open to the objections that, first, there is more or
less difiiculty in securing completeness ‘of precipitation owing
to the rapid increase of free acid* in the solution ; and, second,
the product is extremely susceptible to oxidation. On the
other hand, those methods in which compounds decomposable
by heat are ‘transformed to the dioxide by ignition are gener-
ally both tedious by reason of the length of time required (as
for example, the basic nitrate process as described by Norrist)
and, what is more to the point, liable to errors caused not only
by lack of constancy of composition, but also by the volatiliza-
tion of the product to be weighed.
Of all the forms in which tellurivm has been weighed there
is no doubt that the dioxide is the best. It is unaffected by »
the air, is anhydrous, is not hydroscopic, and can easily be
obtained in pure condition. Likewise it can be heated to any
temperature below low redness without any danger of volatili-
zation. It was in view of these facts that some results obtamed
from an extensive study, about to be published, of the
hydrolytic behavior of hydrochlori ic acid solutions of tellurium
tetrachloride suggested the process about to be described.
When a tetrachloride solution containing the least possible
excess of hydrochloric acid is sufficiently diluted with hot
water, but a small portion, if any, of the tellurium is at first
precipitated. By the addition of as little ammonia in excess
as may be, and the restoration of the acidity by acetic acid in
the faintest possible excess and then allowing the liquid to
stand until cold, the tellurium is precipitated completely, as
TeO,, but in very finely crystalline condition. The precipi-
tate is insoluble in cold water and alcohol, in acetic acid and
ammonium acetate solutions of one per cent strength if cold,
and filters, washes, and dries with the greatest facility.
In the first testing of the method, portions of pure dioxide
were weighed out, dissolved in two cubic centimeters of con-
centrated hydrochloric acid, diluted with two hundred cubic
centimeters of boiling water, and the ammonia, and subse-
* Crane, Am. Chem. J., xxiii, 409. See also Lenher and Homburger, J.
Am, Chem. Soc., xxx, 387.
+J. Am. Chem. Soc., xxviii, 1675.
Browning and Flint—Tellurium Dioxide. 143
quently acetic acid, added with great care. After standing
over night, the liquid was decanted through the asbestos
of a Gooch crucible, and the precipitate transferred and
washed with cold water, and dried to constant weight at
about 105°. In Table I, experiments 1 to 4, are gathered the
results obtained.
TaBLe I.
TeO, taken TeO, found Error
erm. erm. erm.
(1) 0°2002 0°2000 —0°0002
(2) 0°2019 0°2017 —0:0002
(3) 0:2904 0°2002 — 0:0002
(4) 0°2006 : 0°2004 —(0°0002
(5. 0°2011 0°2010 —0:0001
(6) 0°2003 0°2008 0°0000
Jn experiments 5 and 6, one and one-half cubic centimeters
of ten per cent potassium hydroxide solution were used to
dissolve the dioxide, instead of hydrochloric acid. The solu-
tion was then acidified slightly with hydrochloric acid, and the
determinations completed from this point as before. The
results seem to be equally good. 3
Next, weighed amounts of basic nitrate were dissolved in
two cubic centimeters of hydrochloric acid. The small quan-
tity of nitric acid holds up a little of the tellurium* and con- .
sequently before dilution resort was had to evaporation to
remove as much of the free acid as possible. This had to be
done with extreme care, since the least tendency on the part
of the solution to boil was accompanied by the volatilization
of the tetrachloride formed. With a not unreasonable amount
of care, however, good results were obtained. In all of the
experiments of Table II the dilution was with hot water,
two hundred cubic centimeters being sufficient, but in several
the treatment was varied, as given below.
Taste IT.
2TeO2.HNO; TeO. TeO,
taken theory found Error
erm. grm. erm. germ.
(1) 0°2508 0°2094 0°2079 =70 0015
(2) 0°2501 0°2088 0°2086 OO 02
(3) 0°2521 0°2105 0°2101 —0°0004
(4) 0°2500 0°2088 - not completed
(5) 0°2537 0°2118 O°2115 —0°0003
(6) 0°2510 0°2096 0°2091 —0°0005
* Gutbier, Studien iiber das Tellur, 46.
114 Browning and Flint—Tellurium Dioxide.
In experiment I, during the evaporation of the acid, there
was noticed a slight volatilization of the tetrachloride, which
accounts for the increased error. ‘In 2, filtration was per-
formed after twelve hours, and the same length of time
elapsed in 5 and 6. Experiment 8 stood for two hours, and
in this and number 4 potassium hydroxide was used in place
of ammonia. So much tellurium was found in the filtrate
from 4 that the determination was not completed. In 5 and
6, the basic nitrate was dissolved with two cubic centimeters
of ten per cent potassium hydroxide solution, instead of the
usual hydrochloric acid. Before dilution with hot water,
hydrochloric acid was added in very slight excess. The ammo-
nia added in number 6 was so much in excess as to dissolve
completely the precipitate formed. The mereased amount of
ammonium acetate produced in the solution probably held up
a trace of tellurium.
In order to observe the effects produced by variations in the
factors concerned in the process, several experiments were
performed, the figures for which are given in Table III.
TasnieE IIL. |
2TeO.. HNO; TeO, theory : TeO,
taken Te taken as 127°5 found Error
erm. erm. grm. grm..
(1) 0°2502 0°2089 0°2083 —0°0006
(2) 0°2524 0°2108 O-2TLO + 0:0002
(3) 0°2505 0°2092 0°2089 —0°900038
(4) 0°2528 Oa 0°2106 —0:°'0005
(5) Or2 5a O-21135 0°2106 —0:0007
(6) 0°5008 0°4182 0°4182 0:0000
(7). 0°5010 0°4183 O45 —0:'0008
(8) 0°5005 | 04179 0-4178 —0-0001
The first four and the eighth were allowed to stand over
night before the precipitate was removed; in the fifth one
quarter hour, and in the sixth and seventh one half hour,
elapsed. By a comparison of the results it appears that very
little difference is made whether the time allowed to elapse be
trom 15 to 80 minutes or 12 or more hours, so long as the
liquid is thoroughly cooled. }
In all of the experiments of this series, the basic nitrate was
dissolved with ten per cent potassium hydroxide solution, two
cubic centimeters being sufficient in the first five, and four in
the last three numbers. The solution in the case of the —
first two was then acidified slightly with hydrochloric acid,
before dilution with hot water. In the rest, the alkaline
solution was simply diluted with boiling water and faintly
Browning and Flint—Tellurium Dioxide. 115
acidified with acetic acid, the precipitate beimg afterwards
made crystalline* by eaier heating. It was noted that the
precipitate formed by this variation of the method is not so
quickly transformed to the crystalline condition as when the
procedure of the experiments described in Table I is followed.
Tt is, besides, still more finely divided and does not settle quite
so well. There seems to bea distinct advantage in the use of
ammonia, when added to the solution acidified with hydro-
chlorie acid, since, if the diluted solution is sufiiciently hot,
the precipitate formed by the ammonia begins to become
erystalline, apparently, at ‘about the time when tbe point of
neutrality is reached. Under these conditions, a few drops of
dilute ammonia in excess have an inappreciable solvent effect
upon the TeO, and consequently there is also no opportunity
for the shght excess of acetic acid subsequently introduced to
dissolve and thus hold up a trace of the tellurinm. On the
other hand, it seems probable that, when the acetic acid is
introduced, in faint excess, into the hot, diluted solution,
alkaline with potassium hydroxide, since the tellurium is
precipitated in flocecy form which does not become entirely
crystalline until again heated, the excess of acid must dissolve
up a more or less minute portion of the precipitate and retain
it in solution in such a form as not to be again thrown down
upon cooling. Two facts may be adduced in support of this
theory, namely: first, that the errors in Table III show much
greater irregularity than those of Table I; and second, that
whereas the filtrates of I were shown by testing with stannous
chloride to be free from tellurium, several of those in II,
notably experiments 4, 5, and 7, were proved to contain it in
traces.
And finally, the last three experiments of Table III show
that it is perfectly possible to use quite as successfully one half
gram of the basic nitrate, equivalent to four tenths gram of
dioxide, in a single determination, employing a bulk of solution
no greater than 200 to 250 cubic centimeters.
Attempts to separate tellurium from copper and bismuth
by treatment with small amounts of potassium hydroxide solu-
tion, and to estimate the tellurium in the filtrate by this
ammonia-acetic acid process, met with only moderate success.
Under the conditions, the copper and bismuth apparently tend
to form insoluble tellurites undecomposable by the allowable
excess of alkali,t and consequently there was always a loss of
tellurium. And further, if the bismuth or copper is precipi-
tated together with the tellurium, it is practically impossible to
dissolve out from the mixed precipitate all the tellurium by a Lot
* Berzelius, Ann. de Chim. et de Phys., 2 serie, lviii, 134 sq.
+ Ibid., Lviii, 114.
116 Browning and Flint—Tellurium Dioxide.
solution of the alkali. The results of two experiments with
mixtures of bismuth and tellurium oxides are given in
Table LV.
| TasieE LV.
TeO, taken Bi,O3 taken TeO, found é Error
erm. erm. erm. erm.
(1) 0°2027 0°005 0°2015 —0'0012
(2) 0°2009 0.005 0:1997 —0' 0012
In both cases, the mixed oxides were heated with two cubic
centimeters of potassium hydroxide solution (10 per cent), the
precipitate filtered ont, and the filtrate diluted with hot
water and precipitated by addition of acetic acid. |
If hydrochloric acid solutions of tellurium and selenium
dioxides be mixed, abundantly diluted with boiling hot water,
and the operation of the above described process properly
applied, only the tellurium is precipitated, the selenium
remaining entirely in solution in the filtrate. This not only
provides a simple and rapid preparative process for the purifi-
eation of tellurium from selenium, but also makes possible the
estimation of tellurium directly in the presence of the latter
element. ;
TaBie V.
TeO. taken SeO,. taken TeO, found Error |
erm. erm. erm. erm.
(1) 0°2015 On 0°2010 —0°0005
(2) 0°2013 O'l 0°1996 —0:'0017
(3) 0°2003 O°l 0°1992 —0'0011
(4) 0-2009 O°l 0:2008 —0:0006
(5) 0°2000 O°l 0°2002 +0-0002
(6) OFZ2O5 O°l 0°2016 ‘ +0:°0001
(7) 0°2038 Ol 0°2040 + 0°0002
(8) 0°2028 0°05 0°2019 — 0°0009
(9) 0°2024 0°05 0:2024 0°0000
Experiment 1 in Table V was made upon 0:2 grm. of
TeO, in the presence of 0:2 grm. of SeO,, which was later found
to contain a little copper. After solution of the oxides in two
cubic centimeters of hydrochlori¢ acid and dilution to 200 cubie
centimeters with hot water, precipitation was effected as usual
by ammonia and acetic acid. Copper was carried down in the
precipitate, as shown by its greenish color, the total weight
after thorough drying being 0°2054 grm. In order to deter-
mine the amount of TeO, per cent, the precipitate was washed
with ten per cent potassium hydroxide solution, the tellurium
being carried away in solution as tellurite; the residue was
Browning and Flint—Tellurium Dioxide. 117
washed with water until free from soluble matter, and dried
to constant weight, yielding 90044 grm. The amount of
TeO, by difference was consequently 02010 erm. But the
residue, when dissolved in hydrochlorie acid and tested with
stannous chloride, showed the presence of a trace of tellurium.
In experiment 2, two cubic centimeters of the potassinm
hydroxide solution were used, and the hot, diluted solution
acidified with acetic acid. In 3 and 4, after the solution in
two cubic centimeters of potassium hydroxide, hydrochloric
acid was added in faint excess, and the hot, diluted solution
treated with ammonia and then acetic acid; the difference
between these two determinations 1s apparently explained by
the fact that in 3 the solution was allowed to cool a little before
addition of ammonia, and thus the floccy precipitate was
attacked by the acetic acid. In experiments 5, 6, and 7, potas-
sium hydroxide was used to dissolve the oxides, hydrochloric
acid was added to faint acidity, and the dilution made with cold
water, which was then heated to boiling. It was evident that
the flocey precipitation caused by the cold water included some
selenium, which was not released by the change to crystalline
form, since not only are the errors positive, but also the pre-
cipitate, when tested for selenium with So iodide by
the delicate method of Norris, Fay, and Edgerly,* showed the
presence of a trace of that element. In order ‘to be certain
that this is the true explanation of the fact, two more experi-
ments, 8 and 9, were performed, in the first of which special
care was taken to dilute with water. actively boiling, and to
earry out the subsequent operations.as quickly as possible in
order that the change of condition of the precipitate might
occur before the acetic acid was introduced. No selenium
could be detected in the precipitate of experiment 8. In the
ease of 9, the hot solution was allowed to cool somewhat before
the precipitation, in consequence of which the abundant, floccy
precipitate included a minute trace of selenium, as afterwards
proved by the above mentioned test.
In order, therefore, to estimate tellurium as the dioxide by
this method, it is evident that fairly accurate and concordant
results can be obtained by dissolving the material in ten per
cent potassium hydroxide solution, about two cubic centime-
ters for 0°2 grm. of dioxide, acidifying this solution slightly
with hydrochloric acid, diluting to 200 cubic centimeters with
boiling hot water, and precipitating the tellurium in a finely
crystalline form of dioxide from the still hot solution by the
careful addition of dilute ammonia in faint excess and the
restoration of the acidity by the faintest possible excess of
= Am, Chem. J; xxiii, 105.
118 Browning and Flint—Tellurium Diowde.
acetic acid. If these simple operations are properly carried
out, the precipitate will have become crystalline by the time
when the excess of ammonia has been reached; the addition
of a few drops of acetic acid will cause the precipitation to
become entirely quantitative when the solution has cooled, so
that no tellurium will be detectable in the filtrate by stannous
chloride; the precipitate can be transferred, and safely and
rapidly washed with cold water, and dried to constant weight
at abont 105° (or even up to just below low redness) in a
quarter of an hour. Furthermore, the filtration can be per-
formed at the end of half an hour or so, or after 12 to 24 hours,
as most convenient. And, as shown by the experiments of
Table V, selenium does not interfere, providing precautions
are taken.
H.. EF. Merwin—Perouidized Titanium Solutions. 119
Arr. XIV.— Coloration in Peroxidized Titanium Solutions,
with Special Reference to the Colorimetric Methods of
Estimating Titaniwm and Fluorine; by H. E. Merwin.
Tuar the orange-colored solution obtained by treating
titanium sulphate with hydrogen peroxide could be used in
the determination of titanium was made known by Weller.*
In the application of Weller’s method to rock analysis Dun-
ningtont found that in order to obtain results that were at all
satisfactory the pyrosulphate melt usually employed as a means
of rendering the titanium soluble must be dissolved in sul-
phurie acid of at least 5 per cent strength. Bailey and Daw-
sont concluded that the color of such titanium solutions is
due to a soluble form of titanium trioxide. Hillebrand$ has
pointed out that fluorine bleaches this color to a marked
degree. Steiger| has applied this bleaching effect to the esti-
mation of small amounts of fluorine. It is the purpose of
this paper to show that large amounts of alkali sulphates have
a bleaching action similar to fluorine, and further, that both
rising temperature and addition of free acid intensify the
colors thus bleached. Finally, methods of analysis taking
account of these facts are described.
The following solutions were used in the experimental work:
Standard titanium solution containing ‘001 g. TiO, and about
‘1°. H.SO, per 1°. This was made by gently heating an
intimate mixture of 1 g. of TiO, and 3 g. of ammonium per-
sulphate- till the vigorous reaction had ceased, driving off the
ammonium sulphate, treating the residue with 20° of strong
sulphurie acid, heating to fuming and, when cold, pouring into
about 800° of cold water.
The suspended titanium salt soon dissolved, after which
575° of strong sulphuric acid and water to make up to 1000°
were added. If pure TiO, is at hand, this is a most expedi-
tious method of obtaining a solution free from fluorine and
notable amounts of alkali salts. The precaution of precipitat-
ing and weighing the TiO, in 50° or more of the solution
should not be neglected.
Fiuorine solution, containing ‘001 g. of fluorine per 1°,
made from recrystallized, washed, and strongly ignited sodium
fluoride.
* Ber. Deutsch chem. Gesell., vol. xv, p. 2593, 1882.
+ Jour. Am. Chem. Soc., vol. xiii, p. 210, 1891.
{ Studies from the Phys. and Chem. Laboratories of Owens Coll., vol. i,
p. 216, 1893.
§$ Jour. Am. Chem. Soc., vol. xvii, p. 718, 1895.
| Ibid., vol. xxx, p. 219, 1908.
120 HA. &. Merwin— Peroxidized Titanium Solutions.
Sulphuric acid 95-1/2 per cent, sp. g. 1840.
— Hydregen peroxide of ordinary strength.
The standard colored solution was made from the above
solutions. It contained 5° of the standard titanium solution,
2°° of hydrogen peroxide and approximately 3°5°° of sulphurie
acid (including the free acid in the titanium solution), and was
made up to 50°.
The test solutions each had the same volume as the standard,
and contained the same amounts of titanium and hydrogen
peroxide besides varying amounts of sulphuric acid, alkali sul-
phates and fluorine.
Methods of comparing the colored solutions.—During the
early part of the work the comparisons were made by placing
the test and standard solutions each in one of two parallel-
sided glass containers of equal diameters placed side by side.
The standard was then diluted to match the test. By this
method the ratio of the coloring matter in the solutions is
directly proportional to the final volumes of the solutions.
Certain discrepancies appeared in the results of this method
which were found to be due to a tendency on the part of the
observer to overestimate the color in the lett glass. The
amount of overestimation varied considerably, but sometimes
amounted to 6 per cent. For this reason all the later tests
were made with Nessler tubes 6° long and 2°7™ in diameter
held over a white surface illuminated by diffused light. In
making the comparisons the depths of the liqnids in the tubes
were so adjusted that when the tubes were changed right for
left that the left one appeared uniformly darker. .A close
comparison could best be made by focusing the eyes on the
surface six or eight inches in front of where the tubes were
standing, and then lifting the tubes and bringing them momen-
tarily within the field of vision. Solutions thus compared
were first made up to equal volumes, then sufficient amounts of
each were run into the Nessler tubes and the depths noted.
Four to six comparisons were usually made for each set of
solutions. The degree of coloration is inversely proportional
to the depths of the liquids.
The temperature of the solutions was maintained at 21 1/2°—
221/2° C. while they were being matched, except when the -
effects of temperature change were being investigated.
Agents Affecting the Coloration of Peroxidized Titanium
Solutions.
Free acids.—Colored titanium solutions that have been
bleached have their color restored as the acidity of the solution
is increased. Sulphuric, nitric, and hydrochloric acids, and
probably others, produce similar effects. The amount of the
effect in the case of sulphuric acid is shown in detail further
H. EF. Merwin—Peroxidized Titanium Solutions. 121
on in the paper, in connection with studies of the bleaching
agents.
Temperature.—In solutions containing no bleaching agents
changes of temperature of 50° C. intensify the color 5 to 15 per
cent. In the presence of bleaching agents the color is inten-
sified by heating. In certain instances heating 10° C. restores
30 per cent of the color lost by bleaching. (See fig. 1, C.)
Alkali sulphates.—The sulphate sélutions used for the tests
were prepared chiefly from six lots of Baker’s analyzed re-
agents. Sixteen samples of sodium, potassium, and ammonium
carbonates, sulphates and bisulphates were employed. Several
of the samples were converted into pyrosulphates before test-
ing in order to expel any possible volatile impurity that might
bleach the titanium solution, However, such treatment had
but little effect. Definite amounts of sulphates. and of acid
were introduced into test solutions and the amount of bleach-
ing determined. The bleaching produced by equal molec-
ular proportions of the sulphates appears to be equal.
The amount of bleaching for potassium sulphate is indicated
seozmaaiely by the following table of averages from the
tesis :*
Sulphate Acid Bleaching
grams ce. per cent
“= 15
3 2 9
8° 2
°D Sail
6 ie 14
8° =
Fluorine.—The percentage amounts of decoloration by
fluorine in test solutions of known acidity at 22° C. are shown
in fig. 1, B. For example, in a test solution containing 3°5°
of strong sulphuric acid, -0019 e. of fluorine causes a aia
ing of 30 per cent. The depth of the color of the solution is
then 70 per cent of the original. Upon heating, the color is
restored as shown in fig. 1, C,c. At 70° C. the color is only
6 per cent less deep than in a standard solution at 22° C.
Various compounds.—The effects produced by the com.
pounds mentioned in this paragraph are given as determined
by Steiger and as verified or modified by the present experi-
ments. Aluminium sulphate has no marked effect on standard
solutions or on solutions bleached by alkali sulphates, but it
* At least part of the bleaching in faintly acid solutions, attributed by
Dunnington to metatitanic acid, was due to alkali sulphates. Steiger con-
cluded that alkali sulphates have little effect upon the color of solutions
bleached by fluorine. The probable slight excess of acid in his sulphate
solutions would account for his results.
Am. Jour. Sci.—FourtsH Series, Vou. XXVIII, No. 164.—Aveust, 1909.
9
122 H. Bh. Merwin— Perouidized Titanium Solutions.
restores the color to a considerable degree to solutions bleached
by fluorine. Ferric sulphate produces effects similar to alumi-
nium sulphate, and also modifies the color because of the
color of its own solution. Phosphoric acid bleaches a standard
solution. Silica to the amount of °1 g. introduced in the form
of soluble sodium silicate into solutions consider ably bleached
by fluorine, produced no more effect than could be accounted
for by the sodium sulphate generated.
Doubtless there are many other substances that alter’ the
color of peroxidized titanium solutions, but the ones here con-
sidered are the only ones ordinarily encountered in notable
amounts in solutions that would be used for the colorimetric
estimation of titanium or fluorine.
Application to analytical processes.—In the estimation of
titanium by Weller’s colorimetric method a correction must
be made for the effect of alkali salts, if such salts are present
in considerable quantity. The acidity of the solution must be
considered also. .The above table shows the magnitude of the
corrections necessary for solutions containing ‘005 TiO,, and
the amounts of free acid and of normal alkali sulphate ‘indi-
cated. For example, 20 per cent too little, that is 004 2, of
TiO, would be found in such a solution containing 6 2. of
alkali sulphate and 6° total free acid.
For amounts of TiO, more or less than -005 ¢., these cor-
rections will not hold. Twice this amount would require about
half the correction, and half this amount twice the correction.
Inasmuch as the correction can be made smaller by increasing
the acidity of the solution, it is highly desirable to do this.
In rock analysis by using 6 g. of pyrosulphate, which is equiva-
lent to 4 g. of normal sulphate and 2 g. of acid, for the melt
containing the titanium, and dissolving. this in water to which
IL Ort strong sulphuric acid has been added, a nearly negligi-
ble correction of only 3 per cent need be added. If the TO:
exceeds ‘02 2. no correction is required.. In case the melt is
dissolved in 100® of 5 per cent sulphuric acid, the titanium
found—if the amount is een 002 g. and ‘01 g.—is too
low by approximately -0004 @.*
Listimation of Hluorie.—During the progress of this study
it was found that when the Nessler tube method was used, the
percentage ratios obtained by dividing the depth of each solution
bleached by fluorine by the depth of its matched standard,
could be plotted in lines so nearly straight that from the lines
simple formulas could be derived for use in analysis.t
* lt seems safe to conclude that the amounts of titanium in igneows rocks,
estimated colorimetrically, have fallen short by nearly this amount in a
1-gram sample, for as much as 10 grams of pyrosulphate have often been
used, and probably seldom more than 200° of dilute acid.
+ The same ratios are obtained by dividing the final volume of the standard.
by the volume of the test in cases in which a colorimeter is used which
requires the standard to be diluted.
H.. FE. Merwin—Peroxuidized Titanium Solutions. 123
BiG.
A. Coloration in peroxidized titanium solutions in presence of fluorine
and free sulphuric acid. The fluorine in grams is read on the ordinate.
The percentage ratios of depths of color in the standard solution to depths of
color in the test solutions are read on the abscissa. For given amounts of
fluorine and acid the ratio is found above the intersection of the lines repre-
senting the fluorine and acid. The curves are plotted for a temperature of
22° C. The line mM migrates to p as the solution is heated to 82° C.
B. The percentage of bleaching by fluorine may be found from these
curves in the same way that the coloration ratios were found from the
curves of A.
C. Showing the rise in percentage of coloration due to heating. Curve E
for a solution containing 1° of sulphuric acid and ‘0014 g. of fluorine; F
for 3°5°° of acid and ‘0037 g. of fluorine; «@ for 3°5° of acid and ‘0019 g. of
fluorine ; H for a solution standard at 22° C.
124 ZT. &. Merwin—Perouidized Titanium Solutions.
The full lines of fig. 1, A were thus plotted. Suppose
this ratio 7 in a particular case is 142, and that there is -5° of
acid in the test solution, then the corresponding amount of
fluorine is ‘0006 g. The formula expressing this relation is
le Uae
eo g.of fluorine. With 3°5° of acid in the test solution
(
5 FSH MDD : aie ;
the formula is =o. of fluorine. By the conditions of
22,000
the first formula amounts of fluorine between ‘00005 ge. and
‘001 g. can be estimated accurately within -00005 of a gram;
by the last formula amounts between ‘001 2. and -004 2. can be
estimated within -00015 of a gram. By doubling the amounts
of titanium and acid in the test solution and making it up to
100°, -01 g. of fluorine can be estimated.
The above formulas can not be used in rock analysis because
of the disturbing effects of the alkali sulphates necessarily
present in the test solution. In order to make it possible to
know accurately the composition of the solution in which
fluorine is to be determined in rock analysis, the following
method has been worked out.
Two grams of the rock powder are fused with 8 grams of
mixed sodium and potassium carbonates and the fusion is taken
up with hot water. When leached, and without the necessity
for filtering, there are added 8 or 4 grams of powdered ammo-
nium carbonate; the mixture is warmed for a few minutes,
and then heated on the water bath till the ammonium carbon-
ate is destroyed, and the bulk of the liquid is small. In this
way the silica, which otherwise might render the final solution
turbid, is thrown down together with the disturbing alumina
and ferric oxide. The destruction of the ammonium carbonate
is necessary because ammonium sulphate bleaches the final
solution. After filtering there is added to the filtrate—which
should not exceed 75° in volume—3 or 4° of hydrogen per-
oxide, and then cautiously 10° of standard titanium solution*
(containing ‘01 g. TiO,). Including the acid in the titanium
solution, about 4° of strong sulphuric acid are required to
neutralize the alkali carbonates. As soon as neutrality is
reached the solution acquires a light orange color. Neutrality is
tested by adding a little sodium carbonate solution to discharge
the color, and then a drop or two of acid to restore it. The
further treatment depends upon the amount of fluorine
expected. Inthe vast majority of cases this amount is less than
0025 2. (125 per cent of the sample). For such amounts there
js added to the neutralized solution 3° of concentrated sulphuric
acid, and the solution is made up to 100°. After being cooled
* The hydrogen peroxide prevents the precipitation of the titanium by the
alkali carbonate.
H. KF. Merwin— Perouidized Titanium Solutions. 125
to 22° C. the solution is compared with a 100° solution con-
taining ‘61 g. of TiO,, 4°° of H,O, and 2 or 3°° of concentrated
sulphuric acid. The ratio, 7, of depths (or volumes) of the
solutions is obtained as described in the preceding section.
This ratio is, however, much larger than the fluorme would
give, owing to the alkalisulphates. The ratio that the alkali sul-
phates alone would give, if free from interfering substances,
is about 125. Different samples never give quite the same
ratio. Those that give a ratio much higher than 125 probably
contain fluorine. The safest way is to make determinations of
this ratio on two 8-gram portions of the carbonates used in
the fluorine estimation,* and to use this ratio In making the
correction. Having obtained this ratio—call it m—the formula
Fe
23,000 |
Accuracy to one ‘0002 of a gram may be expected. The
probable error is therefore not half as great as with the
standard gravimetric methods.t
If the fluorine expected amounts to 0025 to °0120 grams,
the test solution is made acid with 12° of concentrated sul-
phuric acid, and compared as before described. The formula is
im 3
6,300
not much exceed 108. Accuracy to -0005 g. may be expected.
Thanks are due to Professors J. E. Wolff and T. W.
Richards for suggestions and criticism.
for computing the fluorine is: = grams of fluorine.
=gerams of fluorine: m is to be determined and should
Petrographical Laboratory, Harvard University, May, 1909.
* The 8 grams of carbonates dissolved in about 75°¢ of water are treated
precisely like the filtered fluorine solution.
+ Hillebrand, W. F., The Analysis of Silicate and Carbonate Rocks: Bull.
U.S. Geol. Survey, No. 305, p. 158, 1907.
126 Wiekham—WNew Fossil Coleoptera from Florissant.
Art. XV.—New Fossil Coleoptera from Florissant; by
H. F. Wickuam.
Calosoma Web.
C. calvini n. sp. Represented by a well preserved elytron,
measuring 16°30" from the humeral angle to the apex of the
specimen, the extreme point and a portion of the seutellar
region being lost. Greatest width (about apical two thirds)
590", The sides are approximately parallel, only slightly
broadening from the base to that point, the outer margin thence
regularly arcuate to the tip. The margin is quite broadly
reflexed at the humerus but becomes narrower posteriorly,
and fades out about the broadest part of the elytron. Surface
with about eighteen strize. well impressed and sub-equidistant,
the two exterior somewhat indistinct for about half their
length at base and apex. The fifth stria joins the fourteenth
at a point about 2™™ from the apex, forming an are within
which all the enclosed striz come to an end, while those ont-
side continue nearly or quite to the tip. Interstices rather
faintly but distinctly convex, divided by fine transverse lines
into quadrate spaces which are broader than long; strize plainly
and fairly deeply punctured, the punctures small and distant,
distinct to the extreme apex.
This specimen indicates a species considerably larger than
C. emmonst Seudder, which was also deseribed from - the
Florissant shales, and differs as well in having distinctly
punctured elytral striz. The general arrangement of the striz
near the tip is less like that of the recent C. welcoxe (with
which Scudder compares his C. emmonsz) than of our common
C. calidum, but the fovezee, which can be made out on the
fourth, eighth and twelfth interspaces, were apparently small
as in C. walcowt.
The type, described above, is without exact indication of
locality, being marked simply Florissant, 1908. It was received
from Prof. Cockerell. A second specimen, collected by Mrs.
Cockerell at Station 13, is also referred to this -species. It
consists of an elytron in much less perfect preservation than
the type and portions of two legs, one of which, thougli actually
smaller, shows the tarsal joints to have been proportioned
almost exactly as in C. scrutator. The elytron is somewhat
smaller than the type, measuring about 14", but as far as can
be seen is similarly punctured.
I take pleasure in giving to this fine species the name of
my honored instructor and colleague, Dr. Samuel Calvin, as a
slight recognition of his worth as a man and a geologist. —
Wickham—New Fossil Coleoptera from Florissant. 197
The holotype is in Peabody Museum of Yale University.
Cat. No. 4.
Acilius Leach.
A. florissantensis n. sp. The specimen shows an underside
in only fair preservation, the two hind legs in place and what
appears to be one of the patellate front tarsi, indicating that
the insect was a male. The species is about the size and shape
of our common A. semisulcatus but apparently with shghtly
longer tibze and with the second abdominal segment somewhat
shorter in proportion to the third. Length 18™, width 9°25".
Station number 14. Collection number 257. Received from
Prof. Cockerell. Holotype in Peabody Museum of Yale
University. Cat. No. 5.
No other species of this genus has been reported from the
Florissant shales, and while the specimen in hand is not suffi-
ciently perfect to show many truly specific features, it seems
worth while to characterize it as well as possible, since the
generic facies is quite well marked and so few fossil aquatic
adephagous beetles are known. The genus is represented in
North America by only three species, two of which are very
closely related.
Philydrus Sol.
P. scudderti n. sp. Almost regularly oblong-elliptical,
elongate, evenly and slightly narrowed at each end. Head
large, 1°35"" wide and -70™ long, eyes not defined, antennse
and palpi lacking, except the pseudo-basal joint of one of the
latter which is too indistinct for study. Prothorax short,
broadest just perceptibly in front of the base, sides regularly
and slightly curved to the apex, front angles damaged, apical
margin roundly emarginate, base subtruncate at middle, |
slightly sinuate each side, finely margined, hind angles appar-
ently slightly less than right and somewhat rounded. Sides
of elytra nearly straight to about the middle, thence gradually
regularly rounded to the apex. Sutural margin with very
fine bead. Legs notshown. Scutellum rather small. Length
o°25™™, width 2°65™™.
The surface of this specimen shows a scabrous granulation
which is probably due, in part at least, to the decomposition
of the exoskeleton. It is, however, sufticiently well preserved
to show that the insect was black. On the sides of the
prothorax are some coarse punctures recalling the similar group
in Hydrobius fuscipes.
The specimen almost exactly resembles the description and
figure of TZvropisternus limitatus Scudder, also from the
Florissant field. I should have placed it there had not Dr.
128 Wickham—New Fossil Coleoptera from Florissant.
Scudder definitely stated that no sculpture whatever (except
certain raised lines) was shown in his examples. Further, the
entire facies of my specimen and particularly the small size of
the scutellum lead me to place it in PAdlydrus rather than in
Tropisternus. It is, of course, impracticable to carry the
identification into the groups (based upon palpal characters)
created by the dismemberment of the old genus Phalydrus.
Station number not given. Collection number 51. Received
from Prof. Cockerell. Holotype in Peabody Museum of Yale ~
University. Cat. No. 6.
Podabrus Westw.
P. wheelert n. sp. The type specimen, consisting of obverse
and reverse, shows one elytron entire and a part of the other,
the head, thorax and abdomen, one leg of each pair and both
antennee. Parts of the remaining legs are visible through the
overlying parts of the body.
Head moderate, eyes small, apparently about as in Chaulzog-
nathus pennsylvanicus. Antenne: seemingly eleven-jointed,
moderately slender, the first joint larger, second apparently
about one half as long as the third, the fourth and following
considerably longer, all the joints, especially the proximal ones,
noticeably broader at apex. Prothorax apparently not oreatly
differing i in width from the head, broader than long, truncate
in front. Elytron subtruncate at tip, the disk finely costulate
(probably twice). Abdomen projecting beyond the elytra the
length of two visible segments; another may have been broken
off. Leys moderately stout for this family, the hind ones much
longer than the others. Tarsi all partially mutilated, so that
it is impracticable to describe individual joints, but the tarsus
of the middle leg seems to be of the type shown in the recent
Podabrus comes. The basal joint of this tarsus seems to have
been displaced. Length of specimen entiré 17-25™™, of ely-
trom (dee ort antenna 7-50", of hind femur 5") otsaimad
(MOBY Gee |
Station number 13. Collection number 165. Received from
Prof. Cockerell.
A long study of this insect has resulted in maintaining it 1n
the position given it at first sight. The length of the abdomen
is probably due in part to maceration before the embedding
was completed. The antenne are essentially of a Podabroid
type, and I think the generic assignment is not far out of place.
As will be seen from the measurements, the size is considerably
above the average of the American species of Podabrus, but
this is largely due to what I consider the unnatural extension
of the abdomen. Nothing allied is known from the Florissant
shales. The fact that the: specimen is preserved principally in
Wickham— New Fossil Coleoptera from Florissant. 129
side profile accounts for the lack of comparative measure-
ments of the prothoracic proportions in the foregoing description.
Named for Dr. W. M. Wheeler, who has figured the type
as an undescribed Meloid in the American Museum Journal,
vol. vi, p. 202.
Holotype in Peabody Museum of Yale University. Cat.
Nerf:
Trox Fabr.
T. antiquus n. sp. Form oblong, broader behind, widest
about one third before the apex of the elytra. Head concealed.
Prothorax slightly less than twice as wide as long, broadest at
or very close to the base; sides regularly arcuately narrowing
to apex, which is much narrower than the base; surface finely,
fairly regularly granular, uneven. Base arcuately emarginate
each side for the reception of the elytra, each of which is
ornamented with about eight rows of small granular tubercles,
general surface uneven. ‘There appears to have been a large
tubercle on each side of the suture about one fifth from the
base, but this may be fortuitous. Length 5-75™", width 3°25™™.
Station 14, Mrs. Cockerell. Collection number 274, Florissant
Expedition 1906.
This species seems to have been about the size of a rather
small specimen of the recent 7. equalis, but with sculpture
more resembling 7. atrox.
Type in the British Museum of Natural History.
Meracantha Kirby.
MM. lacustris n. sp.. A profile is shown in fair preservation
exhibiting head, thorax, elytra and three legs, apparently the
hind pair and one of the middle. Head small, antenne
wanting except what may be the basal joint of one. This
joint is quite large and broad, but I believed it to be crushed.
The only palpus showing has the last joint distinctly trian-
gular. Prothorax longitudinally very convex, posterior margin
straight when viewed from the side. Elytra also strongly longi-
tudinally convex. Legs very long and slender, thighs strongly
clavate towards the tip, tarsiobscure. Length 10°50", elytron
fa hind. femur 4°75"", hind tibia 477.
Station number 11. Collection number 222. Received from
Prof. Cockerell. Holotype in the Peabody Museum of Yale
University. Cat. No. 8.
I am not able to decide definitely as to the probable nature
of the sculpture in this specimen. So much variation exists
in the fineness of the different layers of shale that it is frequently
hard to tell characters due to the insect from those dependent
130 = Wickham—New Fossil Coleoptera from Florissant.
on the matrix. However there is an appearance of distant
impressed lines or striz. on the elytra.
The generic reference, naturally, is only provisional; more
pertect specimens may throw the insect in some other genus.
The outline, however, is strikingly like our recent Aleracantha
contracta, but the fossil is considerably smaller and has more
slender femora which are more strongly and suddenly clavate
towards the tip.
Mi ordella Linn.
M. lapidicola n. sp. A species about the size of our recent
M. scutellaris showing the characteristic wedge-shaped form,
long hind legs and anal style of Mordeila and its allies. The
" specimen exhibits a side view in obverse and reverse. Three
legs are visible, one of them belonging to the posterior
pair. Antenne and mouthparts are obscured, and as the slab
of stone in which the specimen is preserved is of coarse texture
the sculpture is obliterated. Probably the insect can be dis-
tinguished from any others which may be discovered in these
shales by the comparative measurements. Length 6°75™™,
anal style, beyond elytral tip, 1:75", hind femur 1°30”, hind
tibia -90™", hind tarsus 1°75™™, first jot of this tarsus -75™™.
Station number KR. 13 B, i908. Received irom sron
Cockerell. Holotype in Peabody Museum of Yale University.
Cat. No. 9.
lowa City, lowa.
F. Ward—Lighthouse Granite near New Haven, Conn. 131
Arr. XVI.—On the Lighthouse Granite near New Haven,
Connecticut ; by Frameman Warp.
Introductory Note.—The Branford granite-gneiss has here-
tofore been considered a single unit of like character through-
out.* While in a general way this is true, yet, from a closer
investigation in both the field and laboratory, it has seemed
reasonable to make a separation of the mass into two types—
the Branford granite and the Lighthouse granite. The differ-
ences between them, while not oreat, are ‘vet thoroughly con-
stant. It is pr oposed | in this paper to consider the latter of the
two types.
LOCATION AND ToPOGRAPHY.
The formation in question is situated on the coast of Long
Island Sound, near New Haven, Conn. Lighthouse Point, on
the east side of New Haven Harbor, is its most westerly point.
From there it extends east to Branford Harbor (four miles in
a straight line). In width (north and south) it varies from a
half mile to over a mile anda half. The accompanying map
(fig. 1) will show its position and extent. On the north it is
bounded by the Triassic formation: the contact line between
them starts at the south part of Morris Cove, passes east and a
little north to the south end of Beacon Hill ; from there it
extends northeast towards a point on the Shore Line division
of the New York, New Haven and Hartford railroad, about
a half mile west of the Branford station. On the east it meets
the Branford granite; the contact between them passes up
through Branford Harbor, keeping about a quarter of a mile
west of Branford Point till it reaches just beyond the trolley
tracks, then passes northwest to the Triassic. On the south
and west the formation passes into the Sound and New Haven
Harbor respectively.
The topography is not striking, that is, there is little relief ;
the highest point in the formation has an elevation of only 120
feet, and fully one half has an elevation of 20 feet or less
above the sea. There are many marshy areas, which are for
the greater part flooded by a few inches of water at high tide.
The shore line is quite irregular with many small bays, inlets,
points, peninsulas and off-shore islands: one large bay opens
off of Short Beach. The shore from Lighthouse Point to Mans-
field’s Grove is made up in a broad way of a series of ares
convex inland. The greater part of the shore has well-exposed
*W.N. Rice and H. E. Gregory, Manual of the Geology of Connecticut ;
Conn. State Geol. Nat. Hist. Surv., Bull. No. 6, 146, 147, 1908.
1382 F. Ward—Lighthouse Granite near New Haven, Conn.
ledges: sandy beaches are not common except in the western
portion. Inland, between the areas of salt marsh, the low hills
have the smooth, rounded outlines commonly seen in this gla-
ciated region: they are usually well wooded, and the slight
depressions between them are freely sprinkled with fresh-
water swamps. These hills show numerous outcrops. Four
or five small quarry openings and a few open cuts along the
trolley lines afford an opportunity of seemg the rock below
the surface.
HisToricat.
The region has been known geologically in a broad way
from very early times. The first geological map of the eastern
JeM(Ghe dL
\ IRIN
AS aoe HX *
wal \ (| re
Fa Ag | YZ;
a
h)
a
be
antored Pr.
LR
!
ob” of po
GSO ¥'¥ yr go Squaw Re
oe
JohnsonPt. Ciam fg? ASumacid.
ret aunton Rock -“Spect
; ~ pala niie
MorganPt. South End ae 9 he. I. 2 wvifes
oe : Confaur Lriteryal 20ft.
SE WL Nie hee : Light House | Branford
Se brane irate.
United States* has Connecticut colored in with “Primary”
and ‘‘Secondary” rocks, referring to crystallines and Triassic
respectively. In the nature of the case there could be no
specific description of any part of the crystallines.
E. Hitchcock,t+ in a description of the formations on each
side of the Connecticut river from Vermont to the Sound,
makes a separation of the granites from the other rocks, but
maps all the granites from Lighthouse Point to Guilford as
one formation.
* W. Maclure, Amer. Phil. Soc. Trans., vi, p. 411, and map, 1809.
+ This Journal (1), vi, 1828.
F. Ward—Lighthouse Granite near New Haven, Conn. 133
J. G. Percival, in the best map of Connecticut up to 1906*
under a description of the Primary rocks, subdivision A 1a,
separates the Lighthouse—Branford granite from the Stony
Creek granite farther east. He notes the pink feldspar and
the gneissic character of the rock in places. While his obser-
vations and mapping were remarkably accurate for his time,
yet the state of geologic science at that period did not permit
any more definite or scientific delineation of the formation.
J. D. Dana mentionst a “ granite or granite-like gneiss” on
Lighthouse Point, but gives no detail of description of the
formation or its extent.
There have been other references to the region by the older
geologists, but only in the more or less vague terms ‘“‘ primary”,
“‘ oranite’, ‘ eneiss’, “ metamorphics”, crystallines”, etc.; no
special descriptions are given and the value of such articles is
practically only historical.
The most complete geological map of Connecticut to-day is
that published by the State Survey.t This, with further
description in the Manual of the Geology of Connecticut,§
brings the knowledge of the region up to date. The Light-
house granite is here included under the Branford granite-
gneiss as one formation. Only a brief outline of the main
characters of the mass are given. The authors state that sufh-
cient data have not yet been accumulated on which to base a
complete description of this rock.
Fietp Gerotoey.
General.—The formation as a whole consists of a medium-
grained granite of pink or reddish color. The structure may
be gneissic, varying from that well-developed and easily seen
in the hand specimen to that which only shows in the mass.
The average hand specimen would not show a well-marked
eneissic structure. It meets the Triassic sandstones, shales and
traps abruptly, the contact throughout being a fault contact.
It grades imperceptibly into the neighboring Branford granite.
The uniform character of the granite of this formation is
moditied by several features, viz.—peginatite, aplite, quartz
veins, inclusions, as well as some variation along the fault
contact. These modifications will be noted in detail, as
follows:
Pegmatite.—Pegmatite is very common throughout the
area. In general appearance it may be described briefly as a
* Report on the Geology of the State of Connecticut, 1842.
¢+ The Four Rocks, with Walks and Drives about New Haven, 1891, p. 89.
tH. E. Gregory and H. H. Robinson, Preliminary Geological Map of
Connecticut, State Geol. Nat. Hist. Surv., Bull. 7.
SW. N. Rice and H. E. Gregory, State Geol. Nat. Hist. Surv., Bull. 6,
pp. 146-147.
1384. PF. Ward—Lighthouse Granite near New Haven, Conn.
very coarse granite. It has two habits of occurrence—(1) True.
dikes having definite directions and with well-defined bound-
aries. But the contact with the normal granite is never
sharp and clear-cut; ata little distance it may seem to be so,
but on closer inspection the pegmatite and granite proper are
found to merge one into the other within a distance of half an
inch. ‘These dikes vary in width from less than an inch up to
as much as ten feet, but six or eight inches is a more common
width. ‘They vary in length from ten or fifteen yards to a
hundred or more. ‘They may be parallel with the gneiss planes
or cut across them in any direction; occasionally ‘their course
is the same as the neighboring joints. In some cases the
smaller dikes are lens-like, thinning out within a few yards;
this kind is apt to have its center portion made up of quartz
alone, changing gradually to the normal quartz-feldspar
mixture as its margin is approached. (2) A large portion of
the pegmatite occurs in irregular patches and smears scattered
through the granite. They do not extend in definite direc-
tions; nor do they have well-defined boundaries, but grade
into the surrounding rock. ‘Their size varies from that of one’s
hand to those several square yards in extent; or there may
be quite large areas which are a heterogeneous mixture of
pegmatite and granite. This patchy type ‘of pegmatite can be
considered as an intermediate stage between true pegmatite
dikes and true miarolitic cavities. The latter, as is well known,
are characterized by irregularity of boundary and direction, and
only differ from the irregular pegmatite of the area in having
cavities in their middle portions. There is no diffieulty in
distinguishing the patchy pegmatite from the miarolitie type;
the relation between them can easily be seen and gradations
between the two can well be imagined. No true miarolitie
cavities have been found in the granite.
The two types—definite dikes and irregular, ill-defined
patches—suggest two periods of pegmatization ; one occurring
while the granitic magma was unconsolidated and in a pasty
condition, another occurring when the magma was all but
solidified into rock, the latter period of course being the time
when the dike type of pegmatite was formed.
Aplite.-—This type of rock is less common than the pegma-
tite. Its occurrence is of two kinds—as in the case of the
other—dikes and irregular streaks. It has the usual fine-grained,
sugary texture. It is simply a finer grained granite with less
ferro-magnesian minerals than normal oranite, | Tle terno-
magnesian minerals may fail utterly at times. The texture
also may be rather coarse occasionally.
Quarte- -veins.—These are common throughout the whole
area. Usually they are small, a few feet to a few yards long,
F. Ward—Lighthouse Granite near New Haven, Conn. 1385
and from a fraction of an inch to six or eight inches in width.
They may cut the rock in any direction, but in a few cases are
found to have a trend parallel to the ‘joints of the locality.
At several points these veins are large, that is are measured
by yards rather than by feet or inches.
Inclusions.—In places and spots throughout this granite
occurs a material which is different from the normal oranite
or pegmatite. It is a well-banded gneiss and may best be
described as a biotite-gneiss injected with granitic magma.
The injection varies from thin lines of pinkish granite material
to broad (half-inch) layers of distinct granite. The granitic
magma has entered the gneiss along its natural structure planes
for the most part, accentuating the original gneissic structure,
but sometimes has eut across the whole in any direction. The
development of large orthoclase crystals has bent the planes of
the gneiss out of alignment; these large feldspars give the
rock in some places a porphyritic appearance Most of the
specimens are over fifty per cent granitic magma, but, on the
other hand, some of them are apparently not injected at all.
In shape they may be slab-like, or they may occur in small
pieces or large blocks. They vary in size from a few inches
to several yards in diameter. Their outlines, while distinct,
are not sharp.
This gneiss is an older rock as is shown by the fact that it
occurs as irregular masses or blocks included in the normal
granite, and also by the tact that in places the injections of
magma can be followed back into the enclosing granite.
It is believed that these included masses are modified frag-
ments of the country rock into which the granite mass as a
whole was intruded; they resemble very closely the Middle-
town gneiss, which occurs in place several miles to the
northeast.
The inclusions occur very sparingly in: the western half of
the Lighthouse granite and are not abundant, on the whole,
even in the eastern part. They are seen well at Mansfield’s
Grove, also at a point upwards of a half ue north of the
Grove along the road.
Contact Phase—There are a few places at or near the con-
tact with the Triassic where the rock has an appearance dif-
ferent from that already described. In the first case the rock
is denser and has a greenish material (chloritic) scattered
through it in streaks and smears or occurring in thin dike-like
planes following the joint directions. Secondly, the rock may
be quite broken in appearance, due to the presence of many
sets of intersecting joints, and may approach the character
of a true breccia. Or lastly the rock may be whitened or
bleached—the result of greater alteration along a fractured
zone.
156 2. Ward—Lighthouse Granite near New Haven, Conn.
Since the above phenomena are largely the result of dynamic
action, they may occur along any fault or fracture zone in this
mass.
PETROGRAPHY.
The Main Granite—Megascopically the rock is seen to be
a typical granite, Le., it is composed chiefly of feldspar and
quartz and has a granular texture. The feldspar is of two
kinds, pink and white, with the pink predominating, and, as
usual where the two kinds thus appear together, the pink is
orthoclase and the white albite. The quartz is commonly oray
and glassy, but in weathered specimens may be coated with a
yellowish hydrated oxide of iron.
Of the accessory minerals biotite is the most noticeable but
it is by no means abundant: it usually occurs as scattered flakes
evenly distributed, but occasionally it may be seen in smeary
segregations or “ schlier en.” Muscovite appears sparingly ; is
more common near Lighthouse Point and in general near the
fault contact. Magnetite, though not appearing in every hand
specimen, can be said to be a common accessory in a broad
way. Garnets have nowhere been encountered: a negative
statement of this kind is only of value when the rock is com-
pared with the Branford granite. The texture is quite uni-
formly medium-grained; there are local exceptions to this
general rule.
Under the microscope the rock is also seen to be a simple
granite as far as mineral content goes. The minerals present
are,—orthoclase, microcline, plagioclase, quartz, biotite, musco-
vite, sericite, chlorite, magnetite, zircon, apatite, (calcite).
The orthoclase greatly predominates over the other feldspars
and presents nothing unusual. Microcline is not present in
any great amount; it shows the usual basket structure. The
plagioclase is practically all albite, only a little oligoclase being
present.
The quartz is characterized uniformly by an undulating and
broken extinction. In some instances it is so broken as to be
granulated. The graphic arrangement of quartz in feldspar
occurs in a few cases.
An occasional flake of muscovite appears in the slides, but
most of the white mica is present as fine scales of sericite scat-
tered through the feldspars or somewhat segregated in cracks
in those minerals.
Biotite appears as the usual brownish, pleochroic flakes.
It may be partially or entirely altered to chlorite. Chlorite
when present is only a product of alteration of the biotite.
Calcite is seen only in those specimens which have been
weathered considerably. Magnetite, zircon and apatite occur
F.. Ward—Lighthouse Granite near New Haven, Conn. 1387
in small amounts with no unusual characters; the quantity of
the latter is small even for an accessory mineral.
Chemical Composition.—The chemical composition of this
granite is given below in column I: the other analyses are
inserted for comparison :
if II ET TE V
BO so SE OAT, 72°47 73°05 TAe23 73°93
Fame eee 732°) | 14-78). 14-58 2 18°64 19°29
a eee 96 57 2°96 1-70 2°91
he Cee “97 e200 1:00 iso
nO et 2S abr "34 Dr a7) 04
0 ae 81 1-27 2°06 2P3;]) Al
K,O Pe ee Had! 4°53 5B) 3°79 4°63
Th ee 3°69 4:08 fe72 3°55 4°66
Bo: ee a oe, 04 dR —— — —
2 Ce 72 48 29 1°72 41
ees "10 alt. — 05 —
UO ieeooaee N.D. N.D. — oli 18
100°10 100°47 100-00 99°95 100°91
I.—Lighthouse Granite, anal. F. Ward.
IIl.—Branford Granite, anal. F. Ward.
II].—Westerly (red) Granite, anal. F. W. Love; used by J. F. Kemp,
Bull. Geol. Soc. Amer., x, 375. ;
TV.—Conanicut Granite, anal. L. V. Pirsson, this Journal, xlvi, 373, 1898.
V.—Quincy Granite, anal. H. S. Washington, this Journal, vi, 181, 1898.
The rock belongs decidedly to the alkalic group of granites,
as is shown by the small amount of R” elements, particularly
lime, and the high alkali content. It is noticeable that the
potash is greatly in excess of the soda.
Alteration —This, while appearing in all specimens to some
degree, is not extensive: none of the ledges is so far
weathered, for instance, as to show any residual soil formation.
In the hand specimen the alteration is shown by the change
of the feldspars. They lose their luster and become whiter
(are kaolinized), and the pink color of the orthoclase is apt to
be lost. The development of hydrated iron oxide also stains
the rock a brownish color. However, quarry specimens taken
only a few feet down from the surface will not show these
signs of weathering ; in many cases specimens only a foot from
the surface will appear fresh to the eye. But along joint or
fracture planes the weathering has been more active and there
the rock may be enough decayed to crumble under slight
pressure.
Under the microscope the feldspars which appeared fresh
to the eye are found to be clouded to some extent with kaolin:
further evidence of change is seen in the development of seri-
Am. Jour. Sci.—FourtTH Series, Vou. XXVIII, No. 164.—Aveust, 1909.
10 ;
1388 4. Ward—Lighthouse Granite near New Haven, Conn.
cite in them: also by the chloritization of the biotite, and
rarely by the presence of calcite.
Dynamic Action.—The rock shows the effect of some dy-
namic force. The evidence for this lies in several facts: (a) The
appearance of the quartz under the microscope—not only does
it show undulatory and patchy extinction, but it is also cracked
and broken so that at times it is well granulated. (b) The
feldspars—there has been a slight cracking along the cleavage
directions, and some of the plagioclase lamelle are curved.
The development of the microcline basket structure seems to
be the result of dynamic action, and where the microcline is
more plentiful it is usually accompanied by a correspondingly
greater breaking of the quartz.
The general effect in its greatest expression is to produce a
eneissic structure. This varies in degree from simple undula-
tory and broken quartz, through specimens where groups of
broken quartzes and occasional micas have a roughly sinuous
parallelism, to those where the material as a whole is distinctly
parallel, shown particularly by the bands of granulated quartz
with some accompanying mica. However, the force could not
have been extreme,—the adjustment of the rock to the strain
was accomplished almost entirely by the breaking of the
quartz, the feldspars showing relatively few eftects.
Feult-Contact Phase.-—The greenish rock already described
as being found in a few places near the fault contact, is seen
under the microscope to be a breccia. All the minerals of the
granite are cracked, fragmented and granulated. The quartz
naturally has suffered the most because of its lack of cleavage.
But the feldspars have by no means escaped the shattering ;
besides the actual breaking apart of the crystals, the plagio-
clase lamellee are bent, folded and faulted; also some micro-
cline has been developed.
As far as mineral content goes, this rock is the same as the
main granite with a few modifications, 1. e., there is no biotite,
for it has all been altered to chlorite, which gives the rock its
greenish cast; muscovite is more abundant,—it occurs as dis-
seminated flakes, or as specks and threads scattered quite
freely in the groundmass and cracks; a little clay has been
developed, both this and the muscovite indicating the presence
of heated waters with the dynamic action.
Figure 2 is a free-hand drawing of a thin section of this rock
viewed with crossed nicols. This shows to what extent the
crystals of quartz (Q) and feldspar (f°) have been broken and —
disrupted. Fragments of these minerals of all sizes fill in the
cracks and interspaces; these with sprinklings of muscovite,
chlorite, a small amount of clay, and a very few accessory
minerals make up the groundmass.
FF. Ward—Lighthouse Granite near New Haven, Conn. 139
The Pegmatite.—The matical of the pegmatite are, as in
the granite, chiefly quartz and feldspar, with a little mica and
some magnetite. The mica is nearly all biotite ; in some cases
it is segregated somewhat along the margins of ‘the dike Ly pe:
There seems to have been no unusnal pneumatolytie action, at
least there are no minerals present which are uncommon in
eranite—not even tourmaline. At one place a little ilmenite
was found with the magnetite.
This non-mineralized character of the pegmatite is a striking
fact. It is most easily explained by simply saying that this
particular magma did not possess any gases containing boron,
fluorine, ete., ‘and so such minerals as tourmaline, topaz, beryl,
ete., could not form. But it is also possible that there might
have been certain zones throughout the magmatic mass which
did not carry pneumatolytic minerals and other zones that did.
Such zonal arrangement or distribution might arise from the
fact that under conditions of high temperature and pressure,
such as would exist in the parent magma, these rarer gases
(perhaps in some other active physico-chemical form) would
act rather as solvents, with the result that no deposition or
formation of any minerals containing them could take place.
But such gases, laden with other elements, on passing up through
pegmatitic channels, would eventually reach regions where the
temperatures and pressures were much lower; here they could
no longer act as solvents, but, by combining with various
elements and by interacting with other materials present,
140 F. Ward—Lighthouse Granite near New Haven, Conn.
would have to form minerals, such as tourmaline, beryl,
fluorite, ete. These zones, then, would be temperature and
pressure zones and would be more or less horizontal in
position.
Under this theory, then, pegmatites that were an integral
part of the rock as a whole and were formed practically
synchronously with it, would not be mineralized, while those
parts of the pegmatite which forced out or reached up into the
very upper portions of the magma or even into the overlying
rocks, would be mineralized. If the surrounding country rock
were super-heated, those portions of the pegmatite nearest the
parent magma would show less mineralization than those
portions farther away, ete.
This theory is only offered as a suggestion.
The texture of the pegmatite varies from a very. coarse
granite to that degree of coarseness where single feldspar
crystals are eight inches long (seen well at Mansfield’s Grove).
Quartz Veins.—In the small type of quartz vein the quartz
is usually glassy and more or less clear; in the larger type it is
usually whiter and duller; either kind may be stained brown-
ish or reddish by iron oxide. The larger also usually has more
or less feldspar present. |
These quartz veins in origin are closely related to pegmatite.
It is a well-known fact that quartz veins are the “end prod-
ucts,” so to speak, of pegmatite and this region should be
no exception. The fact that pegmatites occur whose central
portions are pure quartz, and that quartz veins occur with a
great deal of feldspar, points to the close relation between the
two.
STRUCTURE.
Gneiss Planes.—These do not always show distinctly and
may be so nearly absent as not to show even in a large-sized
hand specimen. Their general strike is northeast and south-
west, with local exceptions. Their dip is towards the north-
west and varies in angle from 0° to 30°; in the western half
of the area they are flatter, averaging 10°, while in the eastern
portion they are steeper, averaging 20°.
Joints.—Joints are very common; any outcrop will show
from one to six or eight sets.. There is hardly a direction of
the compass that has not a joint direction to match it some-
where in the region. But the most common directions (reading
only to the nearest 5° angle) are as follows: N. 5° E., N. 15° E.,
N. 35° E., N. 40° E., N. 60°.E., N.85° EH. N.5° WING ae
N. 20° W., N. 65° W., N. 70° W., N. 85° W. - Jomtsaiivaevame
practically horizontal are fairly common as well.
F.. Ward
Lighthouse Granite near New Haven, Conn. 141
The joint interval varies from an inch or so to several feet.
In some instances the joint faces are well slickensided. Near
the fault contact the joints are so numerous and the interval
so small that they form an intricately interlaced mass of
fractures whose directions it is ;
: : : Fic. 3.
difficult or impossible to deter- ee
. a —— ee =
mie in. some. places, espe- <i ee
pealynear lashihouse ‘Point, 9
Paemeainne care curved «some: ) 77) 8 Te
times these are scattered among — rea ta vie
the regular ones and at other —~ uae se
times they are in parallel series |
as in figure 38. The are of the curve is usually small, a foot
or so across, but may in a few cases be several yards in extent.
The character of the joints varies from place to place. A
good instance of this is in the vicinity of Lighthouse Point ;
the creek (Morris Creek) that separates this point from Morgan
Point is a dividing line,—on the west side, Lighthouse portion,
the joints are numerous, the interval small, and curved joints
are on the whole common; in many places the rock looks
almost shattered ; on the east side the joints are less numerous,
the interval is large, curved joints are rare, and the rock as a
whole much more massive. |
Faults.—The most distinct fault (or series of faults) is the
one separating the granite from the Triassic. The fact that
all members of the eastward-dipping Triassic, anterior, main
and posterior with the imtervening sandstones and shales, in
turn abruptly meet the granite is convincing proof of a fault.
Additional evidence of movement is furnished by the great
abundance of joints near the contact, numerous slickensides,
the brecciated character of the contact granite as seen in thin
section under the microscope. The displacement has been at
least several thousand feet.
Within the granite formation itself there is little evidence
of much faulting. The massive nature of the granite hides
any possible movement. An occasional pegmatite dike shows
a throw of a few inches or perhaps a foot or so. Abundant
joints and slickensides in certain places prove movement but
give no measure of the displacément. Such distinct drainage
lines as Stony River, Morris Creek, ete., suggest fanlting but
do not prove it. Undoubtedly there are many faults as yet
unobserved: they can only be proven by the minute scrutiny
of the jointing, slickensiding, gneiss planes and drainage. As
yet sufficient data have not been accumulated to make definite
statements.
Contact with the Branford Granite.—The Lighthouse granite
merges gradually into the Branford granite. There is no dis-
142 FL Ward—Lighthouse Granite near New Haven, Conn.
tinct line of contact, there are all transitions from the one kind
into the other: there are no stringers or dikes of one kind
leading into the other; there are no inclusions of one in the
other.. These facts, taken into consideration with the fact that
both granites are very much alike miner alogically, chemically,
etc., show that the two are synchronous in origin,—they are
both phases of the same original magma.
AGE AND GENERAL RELATIONS.
It is impossible to determine definitely the age of this rock.
The only formation in the region with a known age is the
Triassic, and the arkose: there is distinctly derived from this
and related granite areas; hence the granite is older than the —
Triassic. It is known to be an integral part of the Lighthouse-
Branford-Stony Creek intrusion, which is in turn one of the
many New England granitic masses. Kemp says* the Con-
necticut and Rhode Island granites are Post-Cambrian and Pre-
Triassic. Dale states+ that the Maine granites are Late Silu-
rian or Devonian in age.
Nothing more definite can be said until the age relations of
other Connecticut formations are better known.
* Bull. Geol. Soc.. Amer., x, 5872, 1899.
+U.S. G. S. Bull, No. 318, p. 11.
W. H. Twenhofel—Silurian Section at Arisaig. 148
Arr. X VII.— The Silurian Section at Arisaig, Nova Scotia ;
by W. H. Twennorer. Witha correlation note by Coarixs
ScHUCHERT. |
[Contributions from the Paleontological Laboratory of Yale University. |
Waite much has been written concerning the Silurian strata
at Arisaig and they have often been studied, no section appears
in the literature assigning the fossils to their proper horizons.
The intermediate position that the fossils of these strata hold
in respect to those vf the United States and Europe has made
such a section particularly desirable. In the summer of 1908
the writer, in the interest of the Peabody Museum of Yale
University, had the opportunity of making a zonal collection
of fossils from this extensive Silurian section and of studying
in detail its stratigraphy.
The writer is under many obligations to Professor Charles
Schuchert, without whose assistance in the analysis of the
fossils the preparation of this article would have been impos-
sible. He is also much indebted to Mr. Alex. J. McDonald
and family, in particular, and to the people of Arisaig, in
general, for many favors accorded him during his stay with
them.
Review of the Literature.—To the writer’s knowledge, the
first person to give any definite statement of the geology of
northern Nova Scotia was Abraham Gesner, who published in
1856 a work entitled: “ Remarks on the Geology and Miner-
alogy of Nova Scotia.” He divided the rocks of the province
into Primary Rocks, Trap Rocks, Clay Slate, and Red Sand-
stone; the last underlying the northern and northwestern areas
(18386 : 1)*
The first reference to the Arisaig rocks is found in a paper
published by J. W. Dawson in 1845, who described the section
as follows: “The section between M’Caras brook (top of
section) and Arisaig is occupied by dark shales and thin layers
of limestone with a few beds of reddish shale and conglom-
2Ce le. Ae The rocks dip southwest, but become much
fractured as they approach Arisaig” (1845:3). He considered
them of Silurian age.
The first paleontological work on the section appears to have
been done about 1850, as in that year Dawson stated that a
small collection of fossils from the upper horizon had been sent
to James Hall, who expressed the opinion that they belonged
to the age of the Hamilton and Chemung groups (1850 : 351),
and statements to this effect appear in his Acadian Geology
* References are to the list of papers at end of this article.
144 W. H. Twenhofel—Silurian Section at Arisaig.
(1855: 315). In later papers he modified this view and
considered that the strata were the time equivalents of the
Clinton to Lower Helderberg of New York, and regarded it as
possible that strata lower than the Clinton might be present
(1868 :573). He further stated that the fauna was interme-
diate in position between that of New York and England.
In 1859 Rev. D. Honeyman, then a minister in the town of
Antigonish, published a short paper in the Transactions of the
short-lived Literary and Scientific Society of Halifax giving
a popular description of the section. Being favorably situated,
he spent much time studying the rocks of this and neighboring
regions and appears to have made a large collection of fossils
from the Arisaig exposures. The results of these and later
studies appeared in a number of papers extending from 1859
to 1887 (See list at end of this article). Basing his conclusions
on Salter’s identification of fossils, he at first considered the
section as extending from the Mayhill sandstone to the Upper
Ludlow, both of Silurian age ; but his later papers express the
view that the section begins in the Ordovician, the Utica and
Hudson River being represented (1886 a: 818), which view
was supported by Hall. He made five subdivisions of the sec-
tion, which he called, beginning at the base, A, B, B’, C, and
D. The most valuable of his papers are those of the years
1864 and 1875. Honeyman deserves a great deal of credit for
his earlier work, his sole stimulus being the love that he had
for the science of Geology.
The most complete detailed description of the Arisaig: strata
occurs in the Report of the Canadian Geological Survey for
the year 1886. Messrs. Hugh Fletcher and E. Rh. Faribault
of the Survey made the section, which from a structural and
petrological standpoint leaves little to be desired, but in failing
to cite the fossils collected their work does not give the strati-
grapher the needed information to determine the historical
record of the rocks described by them. The authors assign
the strata to the Silurian, ranging from the Medina to the
Lower Helderberg.
The latest work is by Dr. H. M. Ami, who gives a provisional
list of fossils, but without locating them in the section. In his
last published statements (1901: 203; 1901 b: 354) with refer-
ence to the section, he applies, beginning at the base, the
names Arisaig, McAdam, Moydart, and Stonehouse to form
divisions of the series; without, however, fixing precise limits
to his divisions.
Location and Boundaries.—The Silurian rocks under dis-
cussion lie upon the Straits of Northumberland, at the httle
village of Arisaig, Nova Scotia. They underlie an area about
six miles long by one and one-half miles wide (1886: 41P),
W. H. Twenhofel—Silurian Section at Avisaig. 145
washed on the north and northwest by the waters of the Straits
of Northumberland and separated from the Pre-Silurian rocks
to the southeast by a great fault. On the shore they are over-
lain unconformably at their western side by a series of con-
elomeratic sandstones of probable continental origin which are
thought to be of Carboniferous age (1886: 89P), the two series
beige separated by about fifty feet of fine-grained amygdaloidal
trap. To the southwest occur a series of continental sand-
stones and voleanic tuffs (1901 : 309) which are considered to
be of Devonian age. These form the Knoydart formation of
Ami (1901 b: 207; 1900 a: 303) and from them he has obtained
fish remains (1900 a: 309) and a series of tracks (1901 a: 33v).
The Silurian is underlain unconformably (?) at Arisaig pier
and to the east by a series of banded hornstones, red conglom-
eratic shale, and syenites (1886 :9P), which in many places have
been broken through or covered by fine-grained amygdaloidal
trap. A part of these rocks Honeyman and Dawson considered
as altered Silurian (1864:339; 1891 :565). Fletcher regards
them as possibly of Pre-Cambrian age, but states that little can
be said of them except that they are older than the “ Medina.”
It is probable that Fletcher is correct, as there appears to be
little evidence for the former view.
Structure.—The entire section is well exposed on the cliff
and reef along the Strait and by several small brooks crossing
it from south to north; two of them, Doctor’s and Arisaig,
which are cut in the lower shales, crossing the entire section.
The structure of the rocks is, according to Honeyman, that of
a synclinal fold (1864: 333); but it can hardly be considered
as a typical syncline, a fact to which he also calls attention
(1864 : 335). “It may be better characterized as a downfaulted
block which has broken south of its mid line, giving rise to a
trough which plunges to the southwest.
This conclusion is derived from the fact that the lowest beds
of the Silurian have not been seen on the southern side of the
area, and by the evidence for faulting given by the topography.
The Silurian hills are separated from Eigg mountain or Maple
ridge, the Cambro-Silurian upland, by a low area called “ The
Marshes,” which extends approximately parallel to the shore
for ten or more miles and marks the fault zone, as Fletcher has
pointed out. The beds are tilted away from this fault zone for
a short distance, but this is what should be expected. The
trough thus formed is much modified by secondary folds and
faults which in the lower part of the section reach a maximum.
Hence the rocks range from a horizontal attitude just west of
the mouth of Arisaig brook. to a vertical and overturned atti-
tude at Beach Hill Cove. The general dip of the rocks of the
shore is toward the southwest.
146) =«W. H. Twenhofel—Silurian Section at Arisaig.
The entire section is much fractured and in many places the
rocks have been crushed literally to fragments. In the harder
rocks the fractures have been filled by quartz and calcite, beg
in many places so well cemented that when struck the rocks
break elsewhere than along the original line of fracture. As.
many as twelve cemented fractures have beén counted ona
fragment three inches wide. This cementation is confined to
the harder rocks, being practically absent in the shales.
The general direction of the fracture lines is, on the average
of those taken, about twenty degrees east of north and thirty
degrees west of north ; but many variations occur. The section
has probably been subjected to pressure more than once in its
history. |
The greatest fault found occurs at the top of zone 12, where
the lower shales have been elevated and abut against higher
limestones. In this case the direction is thirty-five degrees
west of north.
Some of the joint blocks are very symmetrical. In three
beds in which they were particularly regular the following
measurements were taken: N. 20° E. by N. 80° W., N. 380°
W. by N. 702 E., and3N3 28) Wa by IN. 10: We
Petrological Divisions.—The rocks can be divided petrolog-
ically into the upper shales and limestones having their base
on the “ Red Stratum,” the middle limestones and shales, the
middle dark shales, the lower green and dark shales, and the
basal shales and arenaceous limestones. These petrological
divisions foreshadow the paleontological ones, although from
the latter standpoint it is difficult to fix boundaries, as no sharp
break occurs in the section except at the fault at the top of
zone 12. There is a total thickness of thirty-four hundred and
sixty-five feet.
Character and Color of the Rocks.—The rocks comprise
shales, ranging from fine-grained carbonaceous paper shales to
others decidedly coarse and arenaceous, tough argillaceous lme-
stones, rarely pure limestones, flint-like flags, and fine-grained
sandstones. In the lower shales are a few beds of low-grade
iron ore, once worked but now abandoned.
The color of many of the rocks on a wave-beaten surface is
a dirty green, on a weathered surface a rusty yellow or brown.
The shales range through gray, red and black. In the upper
part they are red followed by gray and green shades. The thick
middle shale horizon is of a dark gray color. The upper half
of the lower shales are green ; in the lower half dark to black
colors predominate. The sandstones and flinty flags have some
shade of blue. The limestones range from gray to grayish-
ereen, the latter predominating.
Wel wenhofel—Silurian Section at Arisarig. 147
Manner and Place of Deposition.—The strata were formed
at no great distance from the shore, as is indicated by their
decidedly arenaceous character, the great amount of ripple
marking which is particularly characteristic of the upper levels,
and the lenticular character of the fine-grained sandstones that
are present almost throughout. These last show on a polished
or weathered surface wavy and cut-off lines of lamination indi-
eating rapidly changing wave action.
Fossil Content.—The rocks, in general, are fossiliferous
throughout; only one stratum, the ‘“‘ Red Stratum ” of authors,
being without organic remains. They are particularly abund-
ant in the upper red shales and flags, and at many horizons in
the middle and lower shales. The impure limestones as a
whole contain few fossils, but a series of intercalated nearly
pure limestone lenses have them in more than ordinary abund-
ance. ‘These lenses are of two classes: the one wide, but thin,
contains merely fragments; the other, about three times as
wide as thick, contains many well-preserved fossils, usually of
but one species.
feaised Beaches.—Three well-defined raised beaches stand
above the present one and slope gently to the northeast.
Their heights at Stonehouse brook, the top of the section, are
roughly estimated at twenty-five, seventy-five, and one hundred
and twenty-five feet. East of McAdam brook the lowest
merges into the present one. The lowest two still have very
steep cliffs, so their uplift must have been comparatively recent.
Whether these beaches rise in elevation westward is not known.
Topography.—Vhe faulting and fracturing of the rocks have
had little effect on the upland topography of the area underlain
by the Silurian. The brooks crossing the section flow im deep
and narrow gorges which do not owe their location to the
presence of fractured or faulted zones. Exceptions are
McDonald’s and Arisaig brooks, which have chosen weakened
zones as points for breaking over the shore cliff. The gradi-
ent of all the streams is high, falls are present in each, and all
the evidence points to recent uplift of the region.
In the shore line topography the story is a different one.
Weakened zones have made the smaller detail of the shore.
In the soft shales this is not so marked, but in the hard shales
and interbedded shales and limestones it is particularly evident.
The fractured zones erode readily and the cliff presents a
serrate appearance. ,
The varying hardness of the rocks determines a higher order
of detail, shales zones being the location of coves, hard rocks
forming points. The latter is well shown by the hornstones
of Arisaig pier and by a double example in zone 35, where at
the present time is a prominent point; and this appears to
148
W. HZ. Twenhofel—Silurian Section at Arisaig.
have been true at another period of the shore’s history, as
the first raised cliff has here a point which is a replica of the
lowest one.
Description of the Silurian Section.
In order to facilitate the study of the appearance and dura-
tion of the species in their true time relations the section is
Honeyman Dawson Fletcher Ami
1804 1868, 1891 1886 1901 Twenhofel 1909
| ( Red shales and
Stonehouse limestones.
Formation. Division IVb 97 feet.
Division D. |Upper Arisaig.; Lower Helder- | or
(Lower Hel- | berg or Eg. ‘Stonehouse
derberg or | 1088 feet. | Formation. | Argillaceous
Ludlow) Moydart | (Ludlow) limestones
| Formation. | ! and shales.
| 978 feet.
Red Stratum. - |Red Stratum. | ( Red Stratum.
| d2 feet.
‘Division IVa or |
| Moydart For- j
mation. | Argillaceous
(Approximates | limestones
ake 7A ; reeae Louisville or and shales.
ea a eee ‘Wenlock time) | 347 feet.
Dark shales.
Division III or
& McAdam
L Sy eee Kee | Formation. j Dark shales
\Lower Arisaig. ormation. (Rochester or aval
(CEprn (0 Upper Lian- argillaceous
Upper Llan- PP ian
Division B’. dovery) ‘Upper Clinton dovery) LL SLO RES:
Total thick- or Ep. | 1020 feet.
ness B’, C, D, | 148+ feet. Fault. L
500 feet. ( Green shales
Division II or | with thin
Lower Clinton | 4 risaig Arisaig Tor- sandstones.
Division B. or Ep. | Formation.| mation. 4
170 feet. 345+ feet. (Clinton or | Dark shales
| Lower Llan- with thin
| dovery) | sandstones.
| | 833+ feet.
cae | ( Sandstones,
Division A. ‘Medina or Ki. Division I. j limestones,
200 feet. 182 feet. (Clinton) 1 and shales.
| 2160 feet.
given beginning at the base and extending upward. Forty
zones have been established, the character of the sediments:
These forty zones have been
being the basis for division.
erouped in five subdivisions.
The thickness for each zone has
W. H. Twenhofel—Silurian Section at Arisaig. 149
been measured in all cases except where the beds are much
disturbed or are covered. In the latter cases the thickness has
been estimated or calculated. Figures of attitude are mag-
netic.
Collections were made at over two hundred different levels
in order to delimit any sudden faunal change to definite hori-
zons. The local faunules show that no break in sedimentation
occurred and that the disturbances that the rocks have under-
gone were not extensive except in a single case at the top of
the Clinton. The entire collection reveals a fauna of from 140
to 160 species, a total in harmony with Ami’s list of 1892.
The preliminary identifications of the fossils made by Pro-
fessor Schuchert relate only to known forms or to comparisons
with weil-known species. They are chiefly of brachiopods; as
the equally abundant pelecypods are nearly all undetermined,
awaiting future detailed comparison and description.
Subdivisions of the Arisaig Silurian have been made by four
previous writers, as indicated in the appended table, which
attempts to show the equivalents of the present section in
terms of the older ones.
BASE OF SILURIAN SECTION.
Silurian Division TJ.
Zone 1 is usually regarded as the equivalent of the New
York Medina, but Professor Schuchert states that all the fos-
sils collected belong rather to Clinton time than to the Medina,
and that he has found nothing in the collection indicative of
the Medina.
1. Base of section at Beach Hill Cove. Here are exposed
greenish calcareous sandstones and thick-bedded argillaceous
limestone with some shale. Attitude vertical or even over-
turned. Not seen at Arisaig, where the first strata following
the break in the shore cliff are banded hornstones. This zone
coincides with Honeyman’s Division A (1864: 336), with the
Medina or Division E 1 of Fletcher (1886: 37P), and with the
lower portion of the Arisaig formation of Ami (1901: 354).
7 Thickness estimated at-... 160 feet.
Fossils are scarce and difficult to collect and were found only
in the upper seventy-five feet which is exposed at the east and
west points of the cove. Lingula ef. oblonga, Dalmanella ct.
elegantula, Cornulites flexuosus, and Zaphrentis ef. bila-
teralis.
CLINTON ZonegES.
Silurian Division II, or Arisaig Formation.
Zones 2 to 12 are correlated with the New York Clinton on
150 =W. H. Twenhofel—Silurian Section at Arisarg.
the basis of the presence of JMonograptus clintonensis, Retio-
lites geinitzianus venosus, and Anoplotheca hemispherica.
Division II begins with dark carbonaceous paper shales, and
has in its upper half green shales with fine-grained sandstones.
It is believed to be coincident with Divisions B and B’ ot
Honeyman (1864: 333), to include somewhat more than the
Upper and Lower Clinton or Division E2 of Fleicher (1886:
37P), and to form the upper portion of the Arisaig formation
of Ami (1901: 394).
Tn this division there is an estimated thickness of over eight
hundred feet, which is probably less than the true thickness, as
some of the strata have been lost by faulting.
2. From Arisaig Pier to the Lobster Factory there are no
outcrops. At the middle of Beach. Hill Cove are exposed
about one hundred feet of black carbonaceous paper. shales
that partly or wholly lie below zone 3. Strike almost E.-W..,
but varying ten to twelve degrees either side. Tossils are
scarce, due to the much weathered condition of the shales.
Base of Honeyman’s Division B and Lower Clinton of Fletcher’s
section.
3. Broken down cliff of dark to black rusty weathering
papery shales. Beds much disturbed, and in part the strike is
almost that of the shore.
Estimated thickness __--._ 100 feet.
Fossils abundant: Azoplotheca hemispherica, Anabava anti-
costiana, Lingula ef. oblonga, Acaste downingie.
4. Dark-gray to green and black fine-grained soft shales,
weathering rusty. Much disturbed. Strike N. 50°—70° W.;
dip 30°-50° W., with many variations.
Estimated thickness _..._. 215 feet.
Fossils fairly abundant: dlonograptus clintonensis, Anoplo-
theca hemispherica, Anabaia anticostiana, Cornulites flecuo-
sus, Calymena cf. tuberculata.
5. Dark-gray somewhat papery shales with afew hard bands ;
all weather rusty. Strike variable. N. 60°—70° W.; dip
30°-40° W.
Estimated thickness __-_-- 50 feet.
Monograptus clintonensis, M. priodon chapmanensis, Lretio-
lites geinitzianus venosus, Orbiculoidea tenuilamellata, Dal-
manella elegantula, Schuchertella sp., Chonetes tenucstriata,
Anoplotheca hemispherica, Anabaia anticostuana, A. depressa,
Cornulites flecuosus, C. distans.
6. Dark-gray splintery shale without hard bands. The
base of this zone is about fifteen yards west of the present
W. H. Twenhofel—Silurian Section at Arisaig. 151
mouth of Arisaig brook, but by faulting it is brought to view
in the mouth of the brook. Strike N. 86° W.; dip 16° W.
APHiCkMeSs ——- E Sae 23 feet.
This zone appears to coincide with the base of Honey-
man’s Division B’ and the Upper Clinton of Fletcher’s section.
Fossils: Jonograptus priodon chapmanensis, Dalmanella ele-
gantula, Anabaia depressa, Cornulites distans, and Dalman-
ates Sp.
7. Green arenaceous micaceous shales and fine-grained sand-
stones in beds from one to six inches thick. Much fractured.
Attitude almost horizontal. Strike N. 20-90° W.; dip 0-2° W.
SCIIGAMOS Se < ge ee 30 feet.
Fossils fairly abundant: JMonograptus clintonensis, Orbicu-
loidea tenuilamellata, Dalmanella elegantula, Chonetes
tenuistriatus, Camarotechia near eguiradiata, Anabaia anti-
costiana, Anoplotheca hemispherica (rare), Schuchertella sp.,
Avicula emacerata, and fragments of Hurypterus.
8. Green shales and thin lenticular fine-grained sandstones.
Strata in a small synclinal fold.
Estimated thickness _. _.___ 30 feet.
Fossils very common, especially graptolites: Monograptus clin-
tonensis, M. priodon chapmanensis, Letiolites geinitzcanus
venosus, Orbiculoidea tenuilamellata, Leptena rhomboidalis
(first appearance), Chonetes tenwistriatus, Camarotechia near
equiradiata, Anoplotheca hemispherica (small and rare), Cor-
nulites distans, Avicula ct. rhomboidea, Pterinea honeymant,
Modiolopsis (%) ef. primigenia, Dalmanites sp. and fragments
of Hurypterus.
9. Light-green, more or less arenaceous shales with numerous
lenticular fine-grained sandstones. A shale layer three feet
thick full of Leptwena rhomboidalis occurs. The beds are
much disturbed and thickness is uncertain.
Estimated thickness ____ ___- 66 feet.
Monograptus clintonensis, Chonetes tenuistriatus, Cama-
rotechia cf. obtusiplicata, Phynchonella cf. robusta, Anoplo-
theca hemispherica (rare), Serpulites cf. dissolutus, Cornulites
distans, Avicula rhomboidea, Modiolopsis (?) ct. primigenia,
and Hurypterus fragments.
10. Light-green, soft, somewhat papery shales weathering a
dirty greenish-yellow and many thin lenticular fine-grained
sandstones. This zoue begins at a small promontory forming
the west end of a synclinal fold which is believed to be the
disturbance of zone 18 of Fletcher’s section and ends at a fault
about forty yards east of the mouth of Smith’s brook. This
appears to be the fault described by Fletcher (1886: 39P) and
152. OW. HL. Twenhofel—Silurran Section at Arisarg.
marks the base of his Niagara. Strike N. 55° W.; dip
10°-35° W.
Estimated thickness ---- ___- 66 feet.
Chonetes tenuistriatus, Rhynchonella cf. robusta, Anoplo-
theca hemispherica, Cornulites distans. |
11. Greenish-gray shales with some much shattered lenticu-
lar fine-grained sandstones. Zone ends at a small gulch in the
cliff, that is here forty or more feet high and crowned by
stratified glacial material. Strike N. 54° W. to N. 738° E.; dip
34° W. to 10° E.
Estimated thickness ___-_-_- 63 feet.
Very fossilifterous: Monograptus clintonensis, Retiolites gein-
itzianus, Orbiculordea tenuilamellata, Dalmanella elegantula,
Leptena rhomboidalis, Chonetes tenuistriatus, Camarotachia
cf. obtusiplicata, Wilsonia cf. saffordi, Anoplotheca hemispher-
ica, Cornulites distans, Dalmanites, Conularia.
12. Dark-gray shales, weathering rusty, with very few hard
bands. Beds much disturbed.
Thickness thought to be near __. 80 feet.
Fossils abuudant, particularly graptolites: Monograptus clin-
tonensis, Leptena rhomboidalis. Chonetes tenuistriatus, Ano-
plotheca hemispherica, Modiolopsis (2) ef. promigentius, Caly-
mene, and Dalmanites.
HigHER NIaAGARAN ZONES
Silurian Division IIT, or McAdam Formation.
Following zone 12, the highest member of the Clinton, there
is a fault of considerable importance, the eastern limb of which
has been elevated and a part of the strata lost. The fossils of
zone 13 are markedly different from those below and yet a
number of species, chiefly pelecypods, range on both sides of
the fault. Apparently the throw has not been extensive.
The species of zones 13 to 27 are not many in number; but
indicate, rather distantly however, the Rochester shale. This —
time equivalence is best seen in the presence of J/onograptus
cf. riccartoensis, Dalmanella ef. edgelliana, Camarotaechia
neglecta, C. ch. obtusiplicata, Spirifer crispus, and first
appearance of large Atrypa reticularis. Other species that
help to confirm this correlation could be mentioned, but most
of these have a longer upward range. In fact, all the zones
about the fault have an indigenous fauna that gradually changes |
into those of the higher beds. Division III is believed to coin-
cide, in the main, with the McAdam formation of Ami
(1901: 804), in part with the Niagara or Division E38 of
W. H. Twenhofel—Silurian Section at Arisaig. 158
Fletcher (1886: 37P), and in part with Division C of Honey-
man (1864: 333). It consists chiefly of dark splintery arena-
eeous shales with a total thickness of one thousand and twenty
feet.
13. More or less thick-bedded greenish-gray to dark-gray
rubbly argillaceous limestone and splintery micaceous-arenace-
ous shale. The zone is much disturbed and at its base is
thrown into a small anticlinal fold of which the eastern limb
has been broken off and elevated an unknown distance. Strike
N. 56°-72° W.; dip 32°-37° W.
Estimated thickness ___--_- 140 feet.
If one may judge from Honeyman’s map (1864: 336), this
zone forms the base of his Division C. Fossils abundant:
Mariacrinus (?), Dalmanella elegantula, Leptena rhomboida-
lis, Stropheodonta sp. 1, Camarotechia neglecta, C. ct. obtu-
siplicata, Atrypa peticularis (first appearance).
14. Dark-blue to gray micaceous-arenaceous shales with a
few flags and thin limestones to a large trap bowlder at foot of
eae oirike N. 76° W.; dip 32° W.
pihweleness: 2222228: Sl tds, beet.
Fossils abundant: Dalmanella elegantula, Camarotechia neg-
lecta, Tentaculites, Homalonotus dawsoni (%).
15. Greenish-gray interbedded arenaceous-argillaceous lime-
stone and shale to McAdam’s boat Janding. Zone much dis-
turbed. Strike N.64° W. to N. 57° E.; : dip 42° W. to 39° E.
Much of the shore follows line of strike.
Thickness estimated at_._.. 63 feet.
Pholidops implicata, Dalmanella elegantula, D. n. sp. very
large, like D. edgelliana, Camarotechia neglecta, Pterinea
emacerata, Calymene, Homatonotus dawsoni (?).
16. Dark-gray shales. Strike N. 64° W.; dip 33° W.
BHC TASS RADE OU Neat yo 24 feet.
Fossils common: Dalmanella elegantula, Camarotechia neg-
lecta, Tentaculites.
17. Greenish-gray and wae gray, crumbling, more or less
arenaceous shales. “Strike N. 75° W.; dips aoe WW:
ineksiersiss. Co eS 88 feet.
Fossils searce: Dalmanella elegantula, Camarotachia neglecta.
18. Hard shales, breaking into dagger-like fragments, and
knotty calcareous flags with nearly pure limestone lenses. Strike
N. 80° W.; dip 40° W.
Wineloness 2 5220) aoe! 49 feet.
Fossils scarce: same as in 16 with Chonetes tenuistriatus.
Am. Jour. Sc1.—FourtH Series, VoL. XXVIII, No. 164.—Aveusrt, 1909.
11
154 WW. Hl. Twenhofel—Silurian Section at Arisacg.
19. Dark soft mud-shale with many fossils. Strike N. 72°
W.; dip 40° W.
TERICKMeSS) 32 1e ae, ee eee 24 feet.
Dalmanella elegantula, Camarotechia neglecta, T entaculites,
Bucanella trilobata.
20. Greenish-gray to dark arenaceous shale with more or
less thick beds of argillaceous limestones that are much veined
by quartz and calcite. Zone ends at mouth of McAdam brook.
Strike N. 75°-80° W.; ae 40°—48° W.
Rhvokaees Sate ete ee lO oehOole
Fossils scarce except in a few lenticular limestones: Pholidops
implicata, Dalmanella elegantula, Camarotechia neglecta,
C. ctf. obtusiplicata, Tentaculites, Bucanella trilobata.
21. Black, somewhat papery, soft carbonaceous shales with
no hard bands. Strike N. 64° W.; dip 36° W.
Dinekness* 40202228. 2 Os a3 Osteet:
22. Dark-gray to black carbonaceous splintery shale with a
few hard bands and many oblate spheroidal concretions.
Strike N. 65-80° W.; dip 35-40° W.
Ahickness kc aor am 144 feet.
Dalmanella elegantula, Chonetes tenuistriatus, Camarote-
chia neglecta, C. obtusiplicata, Leptena rhomboidalis, Spiri-
Jer crispus (first appearance), Grammysia (small form), Caly-
mene tuberculata.
23. Dark-gray to black soft carbonaceous shale. Strike
NE Oca ain oi We
Phickness ete. woseeee 17 feet.
Fossils as in 22.
24. Dark-gray to black splintery arenaceous and _ finely
laminated carbonaceous shales. At various levels occur thin
beds of lenticular fine-grained sandstones and very large oblate
spheroidal concretions. Near the top is a bed thickly crowded
with pelecypods. Strike variable but in general N. 70° W.;
with dip 45° W. :
Thicknessica ae 170 feet.
Dalmanella elegantula, Choneétes tenwistriatus, Camarote-
chia neglecta, C. obtusiplicata, Atrypa reticularis, Spirifer
crispus, Grammysia (small forms), Bucanella tritobata.
About thirty-five feet from the top occur Monograptus cf.
riccartoensis in great abundance.
25. Dark-gray to black carbonaceous slaty shales in thick —
beds with some lenticular fine-grained sandstones showing wavy
lines of lamination. Strike N. 48°-54° W.; dip 62° W.
AHI GKMESS*) ts) tok) Palen sae i feet.
W. H. Twenhofel—Silurian Section at Arisaig. 155
Fossils abundant, but poor: Dalmanella elegantula, Chonetes
tenuistriatus, and an abundance of Clecdophorus.
a 2b.” Gray ‘and greenish-gray argillaceous limestones and
slaty flags. Steeply upturned. Strike N. 46° W.; dip 62 WW:
siiniekmess ies. Se 15 feet.
Fossils as in 24. :
27. Greenish-gray argillaceous-arenaceous limestones in thick
beds, many of which are beautifully ripple marked. Strata
much disturbed and thrown into a synclinal fold.
Thickness estimated at_.__- 56 feet.
Division IVa, or Moydart Formation.
This division is not marked basally by a sudden introduction
of new faunal elements and no marked petrologic change
occurs, there being a gradual increase in the amount of lime-
stone with progress upward. The top of Division [Va is drawn
at the upper limit of the “ Red Stratum” or zone 32. The
total thickness is three hundred and seventy-nine feet.
The strikingly new and characteristic species is Chonetes
novascotica that gradually becomes the dominant fossil of
Division [V, attaining to larger and larger size until in Division
IVb specimens are more than one inch long on the hinge line.
Spirifer crispus of Division III is succeeded in 1Va by S. swob-
sulcatus and the latter gives rise to 8S. rugecosta that attains
to typical development and large size in Division IVb.
Division [Va forms the upper portion of Honeyman’s Divi-
sion C (1864: 336), the upper portion of Fletcher’s Niagara
or Division E38 (1886: 38P), and is believed to form the lower
portion of the Moydart formation of Ami (1901: 354).
28. Greenish-gray more or less arenaceous-argillaceous lime-
stone of a prismatic and nodular character, alternating with
thick beds of bluish-gray shale that break into irregular frag-
ments. Strike N. 80° W.; dip 30° W.
Thickness estimated at____ 1i7 feet.
Fossils are scarce but some of the limestone lenses are rich in
them. Large crinoid columns, thick branches of a ramose
monticuliporoid bryozoan, Dalmanella elegantula, Chonetes
novascotica, Camarotechia ct. formosa or borealis, Spirifer
subsulcatus, Pterinea emacerata, Grammysia acadica, Ser-
pulites cf. dissolutus, Orthoceras Sps, ie Diaphorostoma cf.
NUAGATENS1S, Homalonotus dawsoni.
30. Bluish to greenish-gray shales and thin limestones.
Beds little disturbed. Strike N. 75° W.: scapes (3 Ws.
Sle eS Gre tet et Mee 32 feet.
156 «WW. A. Twenhofel—Silurian Section at Arisaig.
Fossils abundant: Chonetes novascotica, Camarotechia cf.
Formosa, Homeospira cf. acadie, H. cf. evax, Spirifer sub-
sulcatus, Orthoceras sp. 1, O. sp. 2, Homalonotus dawsoni.
31. Greenish-gray more or less heavy-bedded argillaceous
limestones, some beds of nearly pure limestone, bluish-gray
mudstones cleaving into thin beds, soft shales, and splintery
arenaceous flags. The zone begins just east of the mouth of
McDonald’s brook. Strike N. 72° W.; dip 36° W.
“Dhickmessiee 4 en pee 101 feet.
Ramose bryozoa as in 28; Camarotechia ct. formosa; an
Eatona medialislike rhynchonelloid, but not at all this
species; Spirifer subsulcatus ; Homeospira cf. acadiae ;
Orthoceras sp. 2; Calymene tuberculata ; Homatonotus daw-
sont; Cornulites proprius. ,
32. The “ Red Stratum.” <A brick-red shale of which the
upper thirty feet is prismatic and locally nodular. Shows
little evidence of stratification except near its base. It is rather
sharply differentiated from the overlying green shales, but
grades into the subjacent zone. Twenty feet below the top is
a nodular band ten inches thick. The nodules are bright green
to greenish-white in color and have their longer axes trans-
verse to the bedding. ‘The same color shows along the fracture
lines. At the base are included twenty-seven inches of thin
beds of ferruginous limestone and shale which form the tran-
sition to zone 31. Strike N. 68° W.; dip 40° W.
Thickness) 2220 2 a eS SF eeeis
Division IVb, or Stonehouse Formation.
This subdivision has its base on the top of the “ Red Stra-
tum” and extends to the amygdaloidal trap at the top of the
Silurian section. It is faunally characterized by the large size
of the species and especially by the abundance of Pholzdops
implicata, Chonetes novascotica, Spirifer rugecosta, Llomeo-
spird, n. sp. 1, Grammysia acadica, G. rustica, Pteronitella
venusta, P. curta, Calymene tuberculata, Acaste logani,
Homalonotus dawsoni, and an abundance of Leyrichia
pustulosa and B. equilatera. The subdivision has a_ total
thickness of one thousand and seventy-five feet. It corre-
sponds to the upper portion of the Moydart formation of Ami
and the whole of his Stonehouse formation (1901:354). It
coincides with Division D of Honeyman, as described in the
Quarterly Journal of the Geological Society of London (1864:
336), and to the Lower Helderberg or Division E6 of Fletcher
(1886: 37P).
W. H. Twenhofel—Silurian Section at Arisaig. 157
33. Very deep-green shales with a few thin lenticular bands
of limestone. Strike N. 58°-66° W.; dip 40° W.
Me KMeSS 0 24 6 Ae ee eno. feeb:
34. Gray to bluish-green, rubbly more or less arenaceous-
argillaceous limestone in thick beds; many of which are of a
lenticular character. In many places ripple marked and much
fractured and veined by quartz and calcite. In the lower beds
occur small black nodules. Strike N. 48° W., changing to
N. 58° W. near the base; dip 40° W.
MINN TGMeS seme. 4 5 os 342 feet.
Fossils not common: Stropheodonta n. sp. 1, Leptena rhom-
boidalis, Chonetes novascotica, Atrypa reticularis, Sprrifer
subsulcatus (large), S. rugcecosta, Homaospira cf. evan.
35. Fauna and beds of same character as in zone 34 except
that the ripple marking is more prominent and characterizes
the zone. Strike N. 38° W.; dip 388° W.
pihieknessiaus] 2-2 eS) Sin he OEfeet:.
36. Greenish-gray quartz-veined rubbly arenaceous-argilla-
ceous limestone in thick beds, and grayish-blue splintery flags
with some green and rusty-purple shale to the mouth of
MePherson’s brook. Often ripple marked. Strike N. 50° W.;
dip 40° W.
PnnVe Messmeiree se oro So del Leet.
Chonetes novascotica, Stropheodonta sp. 1, Atrypa reticularis,
Spirifer rugecosta, Grammysia acadica, Pteronitella venusta.
37. Grayish-green arenaceous shales, argillaceous limestone,
and splintery grayish-blue flags. Much veined and ripple
marked. Strike N. 50° W.; dip 30° W. 5
Ge Rivelneashe 4a eters hi htG7 feet,
Pholidops vmplicata, Chonetes novascotica, Camarotechia cf.
borealis (Davidson’s fig. 224-26), Spirifer rugecosta, Pter-
onitella venusta, Grammysia, Calymene tuberculata, Homa-
lonotus dawsont.
38. Greenish-gray argillaceous limestone and shale with
grayish-blue flinty flags. All in thick beds and much veined
by quartz and calcite. Strike N. 57° W.; dip 37° W.
MICK MESS) okt eye A LO ee tg,
Many fossils. Chonetes novascotica, Camarotachia ct. bore-
alis, Spirifer rugecosta, S. subsulcatus, Homeospira n. sp. 1,
Cornulites proprius (?), Calymene tuberculata, Orthonota
angulifera (4), many bivalves.
39. Red and grayish-green shales, gray and red argillaceous
limestones, and bluish-gray splintery flags to the mouth of
158 OW. A. Twenhofe—Silurian Section at Arisaig.
Stonehouse brook. Very extensively veined by quartz and
calcite. Strike N. 52° W.; dip 438° W.
Thickmess 2.05) cee ere aes 136 feet.
Many fossils: Pholidops umplicata, Chonetes novascotica,
Camarotechia ef. nucula, C. ct. borealis, Spirifer rugecosta,
LHomeospira n. sp. 1, Cornulites proprius (2), many bivalves,
Beyrichia equilatera, B. pustulosa, Acaste logani, Calymene
tuberculatu, Homalonotus dawsoni, Hurypterus or Pterygotus
fragment.
40. Red shales and limestones with grayish-blue splintery flags
dotted with very bright green patches. In the flags the fossils
occur in thin calcareous layers attached to their under sides.
pounke (IN. 63; Wes dip 30> We
AMRICMESS "222i e: Pereyra 97 feet.
Has in addition to the fossils of 39 the following: Schuchertella
subplana, Pteronitella venusta, Bucanella trilobata (large),
Grammysia acadica, Goniophora transiens.
41. Amygdaloidal trap overlain unconformably by Carbon-
iferous (?) sandstone. Apparently has altered neither the
Silurian strata nor the sandstone, but Silurian contact obscure.
Strike of upper contact, NW. 32° E.; dip 23° E.
EKstimated thickness... 40 to 50 feet.
VoLcAntc Rocks AT THE BASE OF THE SILURIAN.
On a previous page mention has been made of the rocks
underlying the Silurian strata and it was stated that these rocks
have been for the most part considered as altered sedimenta-
ries. For complete details regarding them the reader is referred
to the Report of the Canadian Geological Survey for the year
1886, page 9P. Studies made of these rocks in the field led
the writer to the conclusion that practically all are of volcanic
origin, which seems also to have been the view of Fletcher
(1886: 9P). Since, however, they have so often been referred
to as altered sedimentaries, it seemed desirable to investigate
them by chemical and petrological means, and with this pur-
pose in view specimens were collected from Arisaig Pier to
Frenchman’s Barn. These specimens have been studied by
the writer in the Petrological Laboratory of the Sheffield
Scientific School under the supervision of Professor L. V.
Pirsson and in the Kent Chemical Laboratory under the direc-
tion of Professor F. A, Gooch; to each of these gentlemen
the writer acknowledges his indebtedness.
The rocks, as first seen at Arisaig Pier, consist of relatively
light-colored hornstones which show banding to a high degree.
Eastward they become coarser and darker and at the western
W. H. Twenhofel—Sulurian Section at Arisaig. 159
base of the prominent rock mass known as Frenchman’s Barn
appears a bed of red shale containing rounded bowlders overlain
by a thick-bedded series of dark-green stratified rocks. Both
the shale and the dark-green rocks have an almost vertical
attitude. Along lines of fracture all the rocks have a light-
green color and there is a conspicuous irregular band of like
color, varying from fifty ‘to seventy-five feet wide, which is
said to have been traced for more than a mile (1886: 9P).
Throughout the whole, at different points, are younger masses
of amygdaloidal trap.
A chemical examination of the light-colored hornstone of
Arisaig Pier gave the following analysis, which was done in
triplicate to minimize possibilities of error:
SIO ee ee ee ee 67 0, per Cent.
OD Bi Sag a eae ier 1298 «
oe me EE 4 OOo aes
CAO we ee Oba ve
LGR G) Os Oak Base ee eee 0:06 és
Oe sia Be Se FS sk 4°14 e
ee a Re Gee a eae cen em ae, | 9)
aes Bare
12 ONT Uae BS ee oo
BN cali ce Meee Me 1005309.
This analysis corresponds very closely to that of a rhyolite,
as is evident from the high per cent of alkalies present, which
would hardly be the case were the rock an altered sedimentary.
An analysis of the red shale shows that it is, in all probability,
of sedimentary origin. Examination of the rock in thin sec-
tions gave abundant evidence that the hornstones are none
other than rhyolites. The thin sections show that the hornstones
are made up of alternating bands of a very dense and less dense
material, in the latter of which the minerals can be readily
determined. These consist of quartz and alkalic feldspar, the
quartz acting as a sort of sponge for the feldspar and giving
what is known as micropoikilitic structure. Numerous micro-
lites, of which the character has not yet been determined, are
present. Many small flakes of chlorite, along minute lines of
fracture and in places of alteration, explain. the green color
common in many places, and a section made from the green band
shows that the color in this particular section is also due to
chlorite. Pieces of angular fragments, characteristic of extrusive
volcanic rocks, are present in the dense bands. The thin sections
160 3 W. H. Twenhofel—Silurian Section at Arisaig.
show that the dark green rock overlying the red shale is a
voleanic breccia, containing, in addition to the angular frag-
ments of glass and fine material, pieces of quartz and feldspar.
Small flakes of clay are also present, which appear to be due
to alteration subsequent to deposition.
Correlations by Charles Schuchert.
Mr. Twenhofel gathered a large collection of the Arisaig
fossils in over 200 lots from as many horizons in the section of
3465 feet. In looking over this mass of maiéerial one is
impressed with the strangeness of this Silurian fauna, which is
more European in derivation than American. None of the
characteristic Silurian fossils of the United States is present
excepting a few forms like Anoplotheca hemispherica, Cam-
arotechia neglecta, C. obtusiplicata, and a few other brachio-
pods occurring in all Silurian districts. On the other hand,
the pelecypods remind decidedly of Westmoreland, England,
and yet the widely distributed European Cardiola interrupta i is
not present, but is said to occur in northern Maine. Another
peculiarity of this Silurian fauna is the almost complete absence
of corals, but this fact may be ascribed to the muddy and sandy
shore condition of this sea. The only American Silurian
region having a.fauna suggesting direct marine connections is
that of the Appalachian trough, best known about Cumberland,
Maryland.* A comparison with this region shows, however,
that the Arisaig fauna has its own decided characteristics ;
but that it still has by far more in common with the Cum-
berland trough extending to Clinton in eastern New York,
than with the faunas of western New York or the Mississippi
Valley. Another striking fact is that even though the Arisaig
section is a very thick one and though it has been stated more
than once that the Helderbergian faunas or their equivalents
are present, there are no fossils in these strata suggesting
anything more recent than the Ludlow (of the Christiania
area of Norway).
Division [,—This horizon is usually regarded as equivalent
to the Medina of New York; but on grounds other than its
position, there is not the shghtest evidence for this correlation.
As yet no Anoplotheca hemispherica have been gathered here,
but the other fossils are those of Division II. None of the
typical Medina fossils is present and until such are found these
strata are best regarded as of Clinton or Lower Landovery
time.
Division Il or Arisaig formation.—The lowest faunas of
the Arasaig series are distinctly Silurian and there is nothing
present representing the thick transition series between the
* See Prouty, this Journal, Dec., 1908, pp. 553-574.
W.H. T wenhofel—Silurian Section at Arisaig. 161
Richmond and Clinton equivalents, so well developed at Anti-
costi in the St. Lawrence embayment. ‘The section practically
begins with the Anoplotheca hemispherica faunas, clearly of
Clinton time in America and the Lower Llandovery of north-
ern Europe. This biota maintains itself through 800 feet of
shales and sandstones when the continuing deposits are cut out
by a fault of unknown magnitude. ‘To this division may well
be applied Ami’s formational name Arisaig. The guide fossils
of Division II are: Wonograptus clintonensis, M. priodon
chapmanensis, Retiolites geinitzianus venosus (The equivalents
of these graptolites do not appear in the Norwegian section
earlier than the upper division of the Upper Llandovery),
Chonetes tenwistriatus, Anabaia anticostiana, A. depressa
(=Atrypa depressa Sowerby, which appears in the Norwegian
section at the top of the Lower Llandovery and continues
throughout the Upper Llandovery), Anoplotheca hemispherica .
(restricted in the Norwegian section to the Lower Landovery),
Cornulites distans, and Acaste downingie.
The time equivalent of these fossils is clearly Clinton, but
the recent unpublished work of Ulrich and Ruedemann shows
that this formation at Clinton, New York, not only embraces
the Anoplotheca hemispherica fauna, but also continues upward
well into the equivalent of the Rochester of western New York.
The Arisaig Division II is therefore thought to be equivalent
to the lower beds of the eastern New York Clinton, i. e., beds
having Anoplotheca hemispherica, and all of the Lower and
possibly a part of the Upper Llandovery of Norway as recently
described by Kiaer.*
Division IIL or the McAdam formation.— Above the only
pronounced fault of the Arisaig section the strata continue
without interruption to the amgydaloidal trap. Throughout
a thickness of 2575 feet the faunas are continuously of one
progressive development, and one can trace the evolutional
changes of the various elements from small individuals of the
lower beds to the often much larger ones at the top of the
Arisaig section. As this series is a very thick one, it has been
deemed advisable to subdivide it into three divisions, and par-
ticularly so because this has been done by our predecessors in
the same field. |
Division III, consisting essentially of shales, has a thickness
of 1020 feet. The fauna is poorly preserved and is not a large
one, but when the many pelecypods are studied, a longer list
will be at hand than can be given at this time. Many of the
species extend throughout these beds to the top of Division LV.
As guide fossils of Division III may be mentioned Jonograp-
tus riccartensis, Camarotechia neglecta, U. ef. obtusiplicaia,
* Das Obersilur im Kristianiagebiete, 1908.
162 «W. Hl. Twenhofel—Silurian Section at Arisaig.
Dalmanella cf. edgelliana (sometimes compared with D. subca-
rinata), Chonetes tenurstriatus, Spirifer crispus, and Atrypa
reticularis. These fossils, and the absence of the guide Clinton
or Lower Llandovery fossils, seem to indicate that Division
III is to be correlated with the Rochester (probably within the
lower Rochester) and the Upper Llandovery including proba-
bly also the Lower Wenlock.*
Division [Va or Moydart formation.—Basally this divi-
sion is on physical characters inseparable from Division ILI,
and on faunal grounds an arbitrary line of separation is drawn
where the first Chonetes novascotica appear. The top of Divi-
sion [Va is placed at the “Red Stratum,” an horizon noted by
all geologists studying the Arisaig series. The rocks of this
division consist of argillaceous limestones and shales haying a
united thickness of 379 feet. The guide fossils are, earliest
appearance of Chonetes novascotica, suggesting the European
C. striatella; Wilsonia wilsont in typical specimens like
those figured by Davidson trom the Wenlock; a rhynchonel-
loid suggesting Hatonia medialis, but has a lamellose instead
of a striate surface; Camarotechia ct. borealis or formosa ;
Spiriger subsulcatus ; a later and larger development of S.
crispus ; Homeospira acadie ; Orthoceras suggesting the Lud-
low O. striatum; Homalonotus dawsoni ; Calymene tubercu-
lata ; and locally an abundance of ramose bryozoa, but of only
one or two species. Faunally, this horizon is intimately con-
nected with that of Division III, and as the species compare in
development best with those of the middle Niagaran, as the
Waldron and Louisville faunas, the time equivalence of Divi-
sion [Va is thought to be of about this time. In North Europe
the Wenlock has the nearest faunal approach, and according
to Kiaer’s work the Moydart fossils agree best with the Upper
Wenlock of Norway.
Division IVb or Stonehouse formation.—This division
begins basally at the ‘‘ Red Stratum,” and is terminated by the
amygdaloidal trap. The lower 978 feet consist of argillace-
ous limestone and shales, of which about 840 feet have hght
green to gray colors. A red tinge begins to appear in zone
39 and the final 97 feet of zone 40 are of a decidedly brick red
color with some green blotches, and shale predominates here
over the limestone. |
The fauna is essentially that of Division IVa, but the species
have all attained to larger growth and the individuals are
present in greater numbers and better preservation. Chonetes
novascotica is dominant in fine large specimens throughout
this division and in this reminds of the similar development of
C. striatella of the Ludlow horizons ot Norway (see Kiaer).
* See Kiaer, Das Obersilur im Kristianiagebiete, 1908.
W. H. Twenhofel—Silurian Section at Arisaig. 168
Other common fossils are Pholidops implicata (=Crania
acadiensis Hall), Spirifer subsulcatus, S. rugecosta (a devel-
opment out of the previous species and closely related to S.
bijugosa McCoy of Ireland, said to be of Wenlock time), Schw-
chertella subplana (rare), Lhynchonella nucula (a Ludlow
euide fossil), Cornulites flexuosus (reappearance of the lower
form), Bucanella trilobata (much larger than those of lower
horizons), Grammysia acadica (rather indicative of Ludlow),
G. rustica, Goniophora transiens, Pteronitella venusta, P.
curta, Beyrichia pustulosa, B. wequilatera, Acaste logani,
Calymene tuberculata (large), and Homalonotus dawsoni (a
flat-headed form unlike any other American species, attaining
to a length of about three and one-half inches. One imper-
fect specimen of apparently the same form indicates a size of
5 inches or more. This species appears in Division IT).
From this evidence Division [Vb correlates clearly with the
Ludlow. Kaiaer cites Wegalomus gothlandicus from the Mid-
dle Ludlow, and as this fossil occurs in Gotland with Trime-
rella, it would appear that Division IVb has its nearest time
equivalent in the Guelph of Interior America.
Along the shore in the upper part of Stonehouse formation
Mr. Twenhofel picked up the cast of a ventral valve of a large
Spirifer related to S. macropleura and S. niagarensis. The
specimen is out of a brick-red shale and is as large as the
former species but has more plications and is a flatter form, in
both of which characters it approaches S. nzagarensis. This
fossil seems to indicate proximity to Helderbergian (New Scot-
land) deposits, but as it is not S. macropleura, a form also
unknown in the Helderbergian deposits of Dalhousie, New
Brunswick, and Gaspé, Quebec, it does not seem wise to lay
much correlation value upon it for the present.
Bibliography.
1836 Remarks on the Geology and Mineralogy of Nova Scotia (with map).
Abraham Gesner. Halifax.
1845 On the Lower Carboniferous Rocks, or Gypsiferous Formation of Nova
Scotia. J. W. Dawson, Quar. Jour. Geol. Soc. London, vol. i, pp.
30-31.
1850 On the Metamorphic and Metalliferous Rocks of Eastern Nova Scotia.
J. W. Dawson, Quar. Jour. Geol. Soc. London, vol. vi, pp. 347-364.
1855 Acadian Geology. J. W. Dawson, Ist ed., London, p. 315.
1859 On the Fossiliferous Rocks of Arisaig. D. Honeyman, Trans. Lit. and
Sci. Soc. of Halifax. pp. 19-29.
1860 Description of a new Paleozoic Starfish of the Genus Palaeaster from
Nova ann HK. Billings, The Canadian Naturalist and Geologist, vol.
v, pp. 69-70.
1860 On the Silurian and Devonian Rocks of Nova Scotia. J. W. Dawson,
Can. Nat. and Geol., vol. v, pp. 186-138.
1860 Silurian Fossils of Nova Scotia. James Hall, Can. Nat. and Geol.,
vol. v, pp. 144-159.
164. W. H. Twenhofel—Silurian Section at Arisaig.
1860 On New Localities of Fossiliferous Rocks in Eastern Nova Scotia. D.
Honeyman, Can. Nat. and Geol., vol. v, pp. 293-297.
1860 Notes on the Fossiliferous Silurian of Eastern Nova Scotia. J. W.
Dawson, Can. Nat. and Geol., vol. v, pp. 297-299.
1864 On the Geology of Arisaig, Nova Scotia. D. Honeyman, Quar. Jour.
Geol. Soe. London, vol. xx, p. 833-345.
Abstract in this Journal, 2d series, vol. xxxvili, p. 289.
1866 Geology of Antigonish County, Nova Scotia. D. Honeyman, Nova
Scotian Institute of Natural Science, vol. i, pp. 106-120.
1868 Acadian Geology. J. W. Dawson. 2d ed., pp. 565-568, 572-573.
1870 Note on the Geology of Arisaig, Nova Scotia. D. Honeyman, Quar.
Jour. Geol. Soc. London, vol. xxvi, pp. 490-492.
1871 Summary Report of Canada Geological Survey 1871-1872, p. 3, Ottawa.
A. R. C. Selwyn, Director.
1874 Record of Observations on Nova Scotian Geology. D. Honeyman,
Nova Scotian Institute of Natural Science, vol. iii, pp. 6-18.
1874 Paleozoic Fossils. KE. Billings, vol. ii, part i, pp. 129-144, Canada
Geological Survey.
1875 Nova Scotian Geology. D. Honeyman, Nova Scotian Institute of
Natural Science, vol. iv, pp. 47—7Y (?)
1878 Acadian Geology, 5d edition. J. W. Dawson. London.
1878 Nova Scotian Geology: A Retrospect. D. Honeyman, Nova Scotian
Institute of Natural Science, vol. iv, pp. 439-488.
1881 Remarks on Recent Papers on the Geology of Nova Scotia. J. W.
Dawson, Can. Nat., new series, vol. ix, pp. 1-16.
1882 Nova Scotian Geology. D. Honeyman, Nova Scotian Institute of Natu-
ral Science, vol. v, pp. 489-491.
1886 Ann. Report of Canadian Geological Survey, Hugh Fletcher and E. R.
Faribault, pp. 36P-39P.
1886a A Revision of the Geology of Antigonish, Nova Scotia. D. Honeyman,
Nova Scotian Institute of Natural Science, vol. vi, pp. 308-825.
1887 Notes on the Examination of the Silurian Collection of the Provincial
Museum by James Hall. D. Honeyman, Nova Scotian Institute,
Institute of Natural Science, vo]. vii, pp. 14-17.
1888 On the EKozoic and Paleozoic Rocks of the Atlantic Coast of Canada in
comparison with those of Western Europe and of the Interior of Amer-
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797-817.
1888 Abstracts Geol. Mag., 3d Decade, vol. v, pp. 331-382.
Can. Rec. Sci., vol. iii, pp. 182-183, 280-281.
Pop. Sci. Monthly, vol. xxxvi, p. 267, 1889.
1891 Acadian Geology, 4th edition. J. W. Dawson, pp. 560, 565-568, 572-
573, 594-610. Sup. p. 90.
1892 Catalogue of Silurian Fossils from Arisaig, Nova Scotia. H. M. Ami.
Nova Scotian Institute of Natural Science, Series 2, vol. i, pp. 185-192,
1897 Note ona Fish Tooth from the Upper Arisaig series of Nova Scotia.
J. F. Whiteaves, British Association for the Advancement of Science,
Report 1897, pp. 606-657.
1900 Geological Nomenclature in Nova Scotia, Hugh Fletcher. Nova Sco-
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1900a The Knoydart Formation in Nova Scotia—a bit of the ‘‘ Old Red Sand-
stone” of Europe. H.M. Ami, BuJletin Geological Society of America,
vol. 12, pp. 303-3818.
Abstract in Science, Jan. 25, 1901, p. 135.
1901 Synopsis of the Geology of Canada. H. M. Ami, Transactions of the
Royal Society of Canada, vol. vi, section 4, p. 208.
1901a Description of Tracks from the Fine-Grained Siliceous Mustones of
the Knoydart Formation. H. M. Ami, Nova Scotian Institute of
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ya
L. M. Lambe—Fish Fauna of the Albert Shales. — 165
~
Art. XVIUII.—The Posh Fauna of the Albert Shales of New
Brunswick* ; by Lawrence M. Lampe, Geological Survey
Branch, Department of Mines, Ottawa, Canada.
Tue bituminous shales of Albert and Westmoreland coun-
ties, New Brunswick, which are attracting, at the present time,
considerable attention on account of their richness in oil and
sulphate of ammonia, have long been known to hold very
abundant and well-preserved remains of fishes of the family
Palzoniscide. These fishes are particularly numerous at the
Albert mines, where, for some years during the latter half of
. the past century, ane mineral albertite was extracted in pay-
ing quantities. The beds at this locality consist principally of
brown or gray, readily splitting, sometimes almost papery,
‘shales, and nearly black “oil bands” reaching a thickness
often of 6 feet. Associated with the Albert shales, and lying
conformably beneath them, are greenish-gray conglomerates,
the whole having an estimated thickness of about 1000 feet.
The shales are sometimes much disturbed, being in places
faulted and inclined at high angles. They are generally
overlaid unconformably by massive beds of dark-colored con-
glomerate associated with sandstone.
It isin the brown shales principally that the fish remains
occur, but excellently preserved specimens are also found in
_the thick beds as well as in nodules. The majority of the
specimens show the full contour of the fish, with the fins in
-place, but the head is usually so crushed as to obscure the
relationship of its constitnent parts. In many examples very
full details are given of the structure of the scales, fin rays, ete.
and of their surface ornamentation.
Dr. Charles T. Jackson, in 1851,+ described three species
from the Albert mines, viz. '— Palwoniscus alber ti, P. brownia
and P. cairnsii, besides referring to a number of specimens
which were not at the time named specifically.
In 1877{ Dr. Ramsay H. Traquair assigned Paleoniscus
alberti and P. cairnsiz to his genus Rhadinichthys, and P.
brown to Elonichthys.
In the same year§ Sir J. William Dawson added to this
particular fauna by describing Paleoniscus (Lhadinichthys)
*Communicated with the permission of the Director of the Geological
Survey.
+ Report on the Albert Coal Mine, etc., Boston, 1851.
t Quart. Jour. Geol. Soc., vol. xxxiii, p. 559, 1877.
§ Canadian Naturalist, new series, vol. Vili, p. 388, 1878. Part 6, pp.
315-378, published December 1377 rs
166 L. MW. Lambe—fish Fauna of the Albert Shales.
modulus and P. jacksonw. The type material of the former
species was from Beliveau in the northeastern continuation of
the Albert shales area and about six miles, in a straight line,
from the Albert mines; the latter species was based on one
of Dr. Jackson’s largest specimens from the Albert mines
(Paleoniscus sp., fig. 4 of Jackson’s original plate I) in con-
junction with specimens from the same locality in Dawson’s
collection and in that of Dr. G. F. Matthew of St. John, N. B.
Sir Philip Gray Egerton,* and much later Dr. John Strong ~~
Newberry} and Dr. Arthur Smith Woodward,t{ and recently
Dr. Charles R. Eastman,$ have referred to all or some of
these species in greater or less detail.
In a paper, to be published shortly by the Geological Survey
of Canada, on the ‘ Palseoniscid Fishes of the Albert Shales
of New Brunswick,” the writer gives the result of a study of
the fish fauna of the shales of Albert mines and vicinity as.
revealed by the collections of the Geological Survey and by
Jackson’s and Dawson’s type material. The writer takes this
opportunity of expressing his thanks to Dr. Charles R. East-
man and Mr. Samuel Henshaw of the Museum of Comparative
Zoology, Cambridge, Mass., to Mr. Charles W. Johnson of the
Boston Society of Natural History, to Dr. Frank D. Adams
of McGill University, and to Dr. .G. F. Matthew of St. John,
N. B., for the highly valued loan of Dr. Jackson’s and Sir J.
William Dawson’s type and other specimens, without which
the study of this interesting fauna could not have been pro-
perly undertaken.
The Albert shales, primarily held to be of Lower Carbonit-
erous age, principally on the evidence of their fossils, both —
vegetable and animal, have of late been regarded by some
Canadian geologists of repute as properly belonging to the
Devonian. ’ 7
The great similarity of the fauna of the Albert shales of New
Brunswick to that of the shales of the Calciferous Sandstone
Series of Scotland is clearly apparent from the first to any
one studying them and would convince most observers that
these fish-bearing beds in the two countries are synchronous
and belong to the same horizon. The genera of Paleoniscidee
of the Albert shales of New Brunswick are the same as those
of the Scottish shales; the difference is apparent only in the
species, and in these there is a remarkable general resemblance.
The Calciferons Sandstone Series is held by the Geological
Survey of the United Kingdom to form the base of the Car-
* Quart. Jour. Geol. Soc., vol. ix, p. 115, 1853.
+ Paleozoic Fishes of North America, Monographs U. 8. Geol. Surv., vol.
KVig pe Ovi.
t Cat. Fossil Fishes British Museum, Part IT, 1891.
§ Iowa Geol. Survey, vol. xviii, 1908.
L. M. Lambe— Fish Fauna of the Albert Shales. 167
boniferous System in Scotland, and it is the opinion of the
writer that the Albert shales should still, as formerly, be
regarded as of Lower Carboniferous age.
The fish fauna of the Albert mines and vicinity has been
considered for some years to consist of the following species :—
. Rhadinichthys alberti (Jackson), 2. cairnsi (Jackson), LP.
modulus Dawson, EHlonichthys browni (Jackson) and £.
jacksoni (Dawson), and lately Eastman has described a new
form of small size under the name Hlonichthys elegantulus
(Iowa Geol. Survey, vol. xviii, 1908).
After a careful study of all available material the writer is
forced to the opinion that 2. cazrnsz is not distinct from PR.
alberti, that EF. jacksonz is the same specitically as #. brownz,
and that A. modulus is more properly referable to the genus
Canobins of Traquair. The generic position of /. elegantulus
is considered to be problematical; the small size of this
species in conjunction with its generally imperfect state of
preservation leads the writer to suspect that it may be the young
of one of the species already known from the Albert mines,
possibly of PR. alberti. °
This fauna thus appears to consist of the three species
Rhadinichthys alberti, Hlonichthys browns, and Canobius
modulus. To these may be added a fourth regarded as new,
belonging to the genus Elonichthys, and for which is proposed
the name #. e//sz, in honour of Dr. R. W. Ells, who many years
ago obtained the type and only known specimen at the Albert
mines.
The ornamentation of the scales, more especially of the
anterior flank scales, in these species is thoroughly distinctive
and is one of the most useful characters available for the deter-
mination of poorly or partially preserved specimens or even
of scattered scales. |
With the following short descriptions of the four above
mentioned species are given figures of the anterior flank scales
and, in the case of three of them, of the posterior flank scales
also.
RHADINICHTHYS ALBERTI (Jackson).
Paleoniscus alberti Jackson, 1851. Report on the Albert Coal
Mine, etc., Boston, p. 22, plate I, fig. 1, plate II, figs. 2, 2
bis, 3, 4, 5,.8 and ? 6.
Palwoniscus cairnsit Jackson, 1851. Ibid., plate I, fig. 3.
This species is the first of the Albert mine fishes described
by Jackson.
Tt is of small size, rather slender, fusiform, averaging in
length about 85°. Greatest depth of trunk in advance of
the pelvic fins, slightly over one-fifth the total length. Head,
168 L. MW. Lambe—fish Fauna of the Albert Shales.
in length, about equal to the maximum depth of the body.
Eye of moderate size, placed far forward. Fins well-developed.
Dorsal fin beginning a little behind the mid-length of the fish,
triangular, about the same size as, and arising somewhat in
advance of, the anal fin. Caudal fin much prolonged in upper
lobe, deeply forked. Pectoral fins large, with a short base.
Pelvic pair if anything nearer to the anal fin than to the ©
pectorals, of small size. Teeth mmute. Suspensorium oblique.
Anterior flank scales, figures 1 and 2, about as deep as long
(exposed surface), ornamented with striations, of which about
six are fine and parallel to the lower and anterior margins, -
whilst three or four are coarse and have an oblique backward
and downward direction in the upper posterior quarter of the
scale. Posterior margin of scales serrated. Posterior flank
scales with fewer oblique strie, the remainder of the exposed
surface being smooth ; posterior margin with fewer but rela-
tively coarser serrations. Scales of body prolongation of tail
diamond-shaped.
Enlarged ridge scales present from near the head to the dor-
sal fin, and from behind that fin on to and along the upper
lobe of the tail. There are also about three similarly enlarged
scales in advance of the anal fin, and about the same number
between it and the caudal. The enlarged scales are coarsely
and irregularly striated longitudinally, longer than broad, nar-
rowly rounded in front and somewhat pointed behind. Fin
rays jointed throughout, except the principal anterior ones of
the pectoral fins, which appear to be entire proximally. They
subdivide distally and have the appearance of being slightly
striated in the direction of their length. Minute fulera are
present on the margin of the lower caudal lobe and on the
anterior margins of the other fins. The head bones are
orhamented with longitudinal ridges and tubercles, and tran-
sitions between the two.
The seales of the type specimen of /. cazrnsz are well pre-
served with the sculpture particularly definite. The specimen
itself is rather larger than the average sized specimens of 72.
alberti. To the writer the striation of the scales appears to
be the same in both species, poorly preserved in the type of
v. alberti but very clearly shown in the type of /?. cairnsi,
with a like serration of the posterior margin in both. Other
characters distinguishing the two species are not observed and
the conclusion has been reached that there is no real distinction
between the two.
L. M. Lambe—Fish Fauna of the Albert Shales. 169
ELONICHTHYS BROWNI (Jackson).
Paleoniscus brownii, Jackson 1851. Report on the Albert Coal
Mine, etc., Boston, p. 22, plate I, figs. 2 and 5, plate II, fig.
1, and plate I, ? fig. 4.
Paleoniscus browniti and P. jacksonit Dawson, 1877. Canadian
Naturalist, new series, vol. 8, p. 339.
Paleoniscus (lonichthys) brownii and P. jacksonii Dawson,
1878. Acadian Geology, 3d edition, supplement, p. 101.
A species of moderately large size, reaching a length of 87:5"
(about 15 inches).. Maximum depth of the trunk, shiehtly in
advance of the pelvic fins, contained about three and three
quarters times in the total length, Length of head, including
the opereular apparatus, about one-fifth of the total length,
Fins rather large. Pectoral fin powerful, spreading, with a
restricted base; rays articulated except the first two or three
anterior ones proximally. Pelvic fins, small in comparison
with the other fins, about midway between the pectoral and
anal fins, in advance of the mid-length of the trunk. Anal fin
large, triangular, with a broad base, reaching posteriorly close
to the tail. Dorsal fin similar in shape to the anal but not
quite as large, the center of its base nearly above the anterior
end of the base of the anal. Caudal fin large, the body
prolongation of the upper lobe robust, extended, the lower
lobe well-developed. Fulera in all the fins conspicuous.
External bones of the head ornamented with definite ridges
of varying length, straight or slightly tortuous and having a
general longitudinal direction, replaced at times by tubercles.
Flank scales near the head (figure 3), sculptured by
from sixteen to twenty striations running obliquely backward
except in the anterior lower portion of the scale surface where
they are parallel to the lower margin. Posterior margin ser-
rated. Usually in passing backward on the trunk, the striz
decrease in number and gradually disappear, being replaced
by a few punctations, the surface of the scales becoming
smoother and the serrations fewer in number, figure 4, until
in the upper lobe of the tail both punctations and serrations
are lost, leaving the scales smooth. It is found, however, that
the striations of the scales persist in a variable degree, in differ.
ent specimens, in the posterior half of the trunk, and in
some even the caudal scales retain a number of the strie.
Between the dorsal and anal fins the flank scales are nearly
twice as long as high with a considerable overlap, but near
the head they have more the form of a rhombus. The
exposed surface of the anterior flank scales is higher than long.
Enlarged, longitudinally striated, imbricating dorsal ridge
Am. Jour. Scl.—FourRrTH SERIES, VoL. XXVIII, No. 164.—Aveust, 1909.
12
170) L. WM. Lambe—fish Fauna of the Albert Shales.
scales extend in a row from near the head to the dorsal fin,
and from the latter to the extremity of the tail, on the upper
lobe of which they are of modified shape and er adually dimin-
ishing size. Between the anal fin and the tail similar scales
occur. Enlarged, longitudinally striated scales are seen in a
number of specimens, between the anal and ventral fins.
The more anterior dorsal ridge scales are ovate, slightly longer
than broad, becoming more pointed behind on approaching
the dorsal fin. The posterior margin is denticulated.
In the fins, the rays are articulated throughout except the
most proximal part of the first two or three rays of the pecto-
ral. They subdivide distally, and a second and apparently
also a third subdivision may take place, On the front border
of the joints, in the more anterior part of the fins, short
oblique striations are observed. These particular markings are
not observed in the posterior half of the fins, where another
style of ornamentation is developed near the base, viz., a
minute serration of the hinder border of the joints.
The mandibular suspensorium is apparently oblique. The
teeth, as seen imperfectly in one specimen only, seem to be
arranged | in two rows, after the manner of the genus, viz., with
small teeth in an outer row, and larger ones, at intervals,
forming an inner row.
The type specimen of Dawson’s Paleoniscus jacksoni (igure
4 of Jackson’s plate I) is not available for study, but judging
from the figure, and from Dr. Jackson’s remarks on its scale
ornamentation, it appears to the writer probable that it is not
distant from £. brown. A specimen from McGill Univer-
sity museum, labelled P. jacksonz, Hillsborough, No. 2698, has
the scale sculpture and the ornamentation of the joints of the
fin rays such as are seen in Jackson’s type of 4. browné with
which it is evidently conspecific. Among the specimens from
the Natural History Society of New Brunswick is the original
of the one from which the plaster cast, mentioned by Sir
William Dawson in his Acadian Geology, was taken, which
east formed part of the material on which P. jyacksoni was
based. The specimen consists of the posterior part of the fish,
from shghtly in advance of the dorsal fin backward to the end
of the tail. The anterior basal portion only of the anal fin is.
preserved, and the position of the dorsal fin is indicated, but
the specimen is elongated by distortion, and both fins are more
distant from the tail than they otherwise would be. The gen-
eral contour of the specimen is much the same as that of others
in the collections of the Survey similarly distorted, and the
characters of the scales are clearly those of & browni, to
which species the specimen is referred.
L. M. Lambe—Fish Fauna of the Albert Shales. 171
ELONICNTHYS ELLSI sp nov.
A species of small size. Type and only specimen known
about 12™ (4? inches long). Greatest depth a little less.
than one-fourth the length. Head, with opercular apparatus,
one-fourth the total length. Dorsal fin large, arising very
slightly behind the mid- Jength of the fish, and but little in
advance of the anal fin, which is about the size of the dorsal.
Both of these fins are ‘triangular, with a base about equal to
the length of the anterior border. Fulcra are apparently
present on all the fins; plainly seen on the dorsal and anal
fins. Of the ventral and pectoral fins, a few rays only are
preserved, which serve as an index to the fins’ position. Ven-
tral fins rather closer to the anal than to the pectoral fins. The
fin-rays are articulated, except the principal ones of the pecto-
ral fins, which are entire, at least, proximally; they are finely
striated in the direction of their length. The tail is deeply
forked. Scales of moderate size; about as deep as broad on
the flank anteriorly, figure 5, where they are ornamented with
nine or ten conspicuous, narrow ridges, directed backward and
deeply serrating the posterior border. Posterior flank scales,
figure 6, less highly ornate, and with few but well-marked
serrations posteriorly. Scales of the caudal body prolongation
nearly smooth. Enlarged scales extend along the dorsal ridge
in a row, in advance of the dorsal fin, to the head, and behind
the same fin backward to the termination of the upper lobe of
the tail. Similarly enlarged scales occur between the anal fin
and the lower lobe of the tail, with a few, probably three or
four, in front of the anal fin. Head-bones marked by irregu-
lar, short ridges, and tubercles. Suspensorium apparently
oblique.
The ridges of enamel on the anterior flank scales constitute
the most conspicuous feature of the scale ornamentation of this
species. These ridges, nine or ten in number, are mainly
developed on the posterior half of the scale, and have the
appearance of rows of connected tubercles. A few fine striz
occur near and parallel to the lower margin of the scales.
The enlarged ridge scales are rugosely and _ irregularly
striated longitudinally, and are toothed behind. Conspicuous
horizontal striations or linear depressions occur in the moditied
scales of the caudal ridge.
The most distinctive character of the species is the style of
ornamentation of the anterior flank scales, which is different
from that of any other of the Albert shales fishes, and, so far
as the writer 1s aware, from that of any species of the
Paleoniscide.
The species is named after Dr. R. W. Ells, to whom we are
indebted for the one and only specimen known. This speci-
men constitutes the type of the species.
172) L. WM. Lambe—Fish Fauna of the Albert Shales.
CaNoBius MODULUS (Dawson).
Palwoniscus (Rhadinichthys) modulus Dawson 1877. Canadian
Naturalist, new series, vol. viil, p. 338, figs. a-d; and 1878,
Acadian Geology, 3d ‘edition, supplement, p-. 98, “fios, isa—d.
This fish is short and robust, the mandibular suspensorium
is apparently nearly vertical, the head is blunt in front, and
enlarged ridge scales, in a row, pass backward from the occiput
to the dorsal fin and occur again in advance of the candal fin.
These characters suggest its being referable to Traquair’s
genus Cunobius rather than to Lhadinichthys, to which genus
it was assigned when first described.
It reaches a length of 59™™" with a depth in advance of the
dorsal fin of 15™™". The length of the head, including the oper-
cular apparatus, is a little less than one-fourth of. the total
length. The snout is rounded and projects beyond the lower
jaw. The orbit is large and placed far forward. ‘The bones
of the head are ornamented with well- defined, short vermicn-
lar ridges, and tubercles, the former being generally in the
direction of the bone. The mandibular suspensorium is nearly
vertical and thus differs from that of 2?hadinichthys, which is
oblique. The dorsal and ventral fins are triangular and of fair
size, the former shghtly larger than the latter. The dermal
rays are delicate and seem to bifureate distally; they are articu-
lated, with the exception of the principal ones of the pectoral
fins, which apparently are not articulated, at least proximally.
Fulera occur on all the fins. The anal fin is opposite the
dorsal, and the ventral pair is slightly closer to the anal than to
EXPLANATION OF FIGURES.
FicuRE 1. Rhadinichthys alberti, anterior flank scales from a specimen
from the Albert mines, in the collection of the Geological
Survey ; eight times the natural size.
FIGuRE 2. Rhadinichthys alberti, anterior flank scales from the type of
R. cairnsi; similarly enlarged.
FiGuRE 8. Elonichthys browni, flank scales, from two rows next above the
lateral line, midway between the head and the dorsal fin, in
the type specimen ; six times the natural size.
FicuRE 4. Elonichthys browni, flank scales next above those of the lateral
line, beneath the front end of the dorsal fin in the type
specimen ; six times the natural size.
FIGURE 9. Elonichthys ellsi, anterior flank scales from the type specimen ;
enlarged eight times.
Fiaure 6. Elonichthys ellsi, posterior flank scales, from a little above the
mid-height of the body in line with the back part of the
dorsal fin ; similarly enlarged.
FIGURE 7. Canobius modulus, anterior flank scales, from the two rows
beneath the lateral line scales, in the type specimen from
Beliveau, N. B.; twelve times the natural size.
FiguRE 8. Canobius modulus, posterior flank scales, beneath those of the
lateral line, in the type specimen; similarly enlarged.
L. M. Lambe—fish Fauna of the Albert Shales. 178
PALZONISCIDE.
174 LL. M. Lambe—Fish Fauna of the Albert Shales.
the pectorals. The caudal fin is heterocereal and deeply forked,
the body prolongation in the upper lobe tapering gradually.
The seales are rather coarsely sculptured. In the anterior
flank scales, figure 7, the sculpture consists of two or three
delicate but distinct well-defined ridges in the lower half of
the surface, parallel to the lower margin, with three to five
short, prominent ridges in the upper halt of the scale; these
latter are directed obliquely backward and downward in a
somewhat divergent manner from a slightly raised but ill-
defined area confined to the upper, anterior portion of the
scale. The posterior edges of the flank scales are coarsely
toothed, three or four being the usual number of the denticu-
lations. In passing backward the surface ridges of the scales,
figure 8, are reduced in number as are also the denticulations
of the posterior margins, until posteriorly, in the small diamond-
shaped scales of the caudal body prolongation, all trace of
sculpture is lost and the surface of each scale is smooth.
Enlarged, ovoid, imbricating seales, with well-marked longi-
tudinal ridges, extend along the median line of the back, in a
single row, from the head to the commencement of the dorsal
fin, and from behind this fin to the caudal, on which they are
continued as large fulcra-like modifications decreasing in size
posteriorly. On the ventral surface similar enlarged scales
occur between the ventral and anal fins and between the latter
and the base of the caudal, where they give place to small fulcra
on the lower margin of the tail. Of the flank scales the largest
are those of the lateral line.
Two specimens from Beliveau, N. B., of which one is the
type, and one specimen from Horton, N.S8., constitute the type
material of this species.
Canobius modulus has about the same length as C. ramsayt
Traquair but is not so deep. The scales are differently seulp-
tured and in this respect the species is distinct from all other
described ones of the genus.
EF. M. Kindle—Diatomaceous Dust. 195
Art. XIX.—Diatomaceous Dust on the Bering Sea Ice
Floes* ; by E. M. Kinpie.
In ordinary seasons the winter’s accumulation of ice in
Bering Sea disappears to a sufficient extent by the end of the
first week in June to offer no serious obstacle to navigation.
The ice conditions during the spring and early summer of 1908
in Bering Sea were very unusual, however, and all of the
steamers sailing for Nome in June were imprisoned for brief
periods in the Bering Sea ice packs. Most of the vessels
occupied from 8 to 10 days in working through the 300
miles of ice floes which lay between the Seward Peninsula and
the open water in the southern part of Bering Sea. The
steamer Umatilla, on which the writer was a passenger, first
encountered the ice pack off the southwest coast of Nunivak
Island, June 11, in scattermg cakes. During the succeeding
eight days, which the vessel spent among the ice floes, the
opportunities were favorable for observing the character of the
materials appearing upon the surface of the ice and for collect-
ing samples of the dirt on the floes.
At the time of the writer’s observations the long-continued
attrition of the ice cakes comprising the floes had broken them
into pieces generally not exceeding 200 feet in diameter. A
few cakes much larger than this still remained, however, and
one was observed with a length of not less than 350 yards.
A very large percentage of the ice cakes were more or less
discolored by dirt or dust. Probably 80 per cent of the ice
bore small amounts of fine dust or dirt in sufficient quantity to
give it a slight gray or blackish color in spots. No pebbles or
rocks of any kind were observed on the floes. The very fine
texture of the dirt together with its dissemination through the
snow on the ice suggest that most of it reached the surface
of the ice through transportation by the wind. This fine
material was observed to show a strong tendency to segregate
itself into little pellets as the melting of the snow and ice con-
taining the dirt proceeds. These ranged in size from bird shot
up to the size of peas. ‘They were nearly or quite spherical and
in the case of the larger ones sufficiently firm and compact to
probably reach the bottom without dissolution on the complete
melting of the ice in shallow water lke that of the northern
half of Bering Sea.
The color of the dust seen on the ice was generally gray,
dark brownish or black. A sample of the black dust which
was examined by Mr. A. Knopf at the writer’s request is
stated by Mr. Knopf to be unquestionably of voleanic origin.
It may represent a fall of voleanic dust which occurred Novem-
* Published by permission of the Director of the U. S. Geol. Survey.
176 E.. M. Kindle—Diatomaceous Dust.
ber 2, 1907, and covered an extensive area in northwestern
Alaska, including the greater part of the Seward Peninsula.
Samples of the gray dust show very fine-textured earthy
material of about the same degree of coarseness as is seen
ordinarily in the loess.
An interesting feature of these samples of ice-borne dust is
the presence in most of them of considerable numbers of
marine diatoms. These organisms are quite as abundant in the
dust sample which is chiefly of volcanic origin as in the gray
non-voleanic dust. Through the kindness of Dr. Albert
Mann, the writer is able to present a list of the species which
were found in the samples collected. These were obtained
from the ice floes about 30 miles northwest of Cape Romanzof.
The list which follows gives the species which were recog-
nized by Dr. Mann:
List of Diatoms from Ice Floes ; by Albert Mann.
“T find the dust collected on ice-floes in Bering Sea to be fairly
rich in diatoms. Below are the species found therein :
Coscinodiscus radiatus Khrenb.
Coscinodiscus subtitis Ehrenb.
Coscinodiscus curvatulus Grun.
Coscinodiscus excentricus Khrenb.
Coscinodiscus lineatus Khrenb.
Coscinodiscus robustus Grev.
Coscinodiscus spec ?
Coscinodiscus pustulatus Mann.
Biddulphia aurita (Lung.) Breb. & God.
Melosira sulcata (Enrwnb.) Kutz.
Actinoptychus undulatus
Navicula brasiliensis Grun.
Navicula fontinalis Grun.
Coscinodiscus upiculatus Khrenb.
Gyrosigma thuringicum (K.) Rab. See Wm.
Smith’s Synop. Brit. Diatoms; Vol. 1; Pl. 21;
Fig. 205 ; p. 65. Mann, Diat. Albatross Voyages:
p. 366.
“This last species should retain its well known name
Pleurosigma angulatum W.Sm.
“The first named species, C. ’adzatus, is by far the most
common. It may be of interest to note that the above species
were found by me in the dredgings of the 8. 8. Albatross,
made in the southern part of Bering Sea, mostly at consider-
able depths. The new species, a Pustulatus, Mann, was
found at a depth of over 1800 fathoms.
“ Coscinodiscus spec? is an unnamed species. I found this
also in the Bering Sea dredgings and mentioned it in my
FE. M. Kindle—DMiatomaceous Dust. 7
report as C. Heteroporus, Ehrenb. The specimen I marked
as doubtful. I find several examples of it in these samples and
am able to recognize it as identical with the imperfect valve I
found in the Albatross material.”
Diatoms have not been observed before on the Bering Sea
ice and the recorded occurrences of these organisms on floating
ice elsewhere are not numerous. The careful observations of
Nansen* have shown, however, that the presence of diatoms
ieee
Fic. 1. View of an ice cake showing discoloration of front and left sides
by diatomaceous dirt, with pool of fresh water in the center.
on the circumpolar ice packs is not an unusual or accidental
circumstance, as was formerly supposed. Many species of
diatoms were found by Nansen, during the drift of the Fram,
to be living in the shallow pools of water on the surface of the
floating ice cakes. Vanhoffen+ found on the west Greenland
* Fridtjof Nansen, the Norwegian North Polar Expedition, 1893-1896,
Scientific Results, Protozoa on the ice floes of the North Polar sea, vol. v,
pp. 0-6, 1906.
+ The Norwegian North Polar Expedition, 1893-1896, Scientific Results,
vol. iv, 1904, p. 8.
178 E. M. Kindle—Diatomaceous Dust.
coast that diatoms resort to the under surface of the ice in
abundance and are able to live there.
The abundance of diatoms in all of the samples of dirt col-
lected from the Bering Sea ice suggests that the normal habitat
of some of the species obtained for part of the year is the shal-
low ponds of fresh or brackish water on the ice cakes. One of
the pools from the margin of which diatom-bearing dirt was
obtained is shown in the photograph, fig. 1. Some of the
species may attach themselves to the under surface of the ice
as observed by Vanhoffen in the early winter while it is thin,
become frozen in and reach the upper surface by the melting
of the upper layer of the ice in early summer.
The siliceous tests of these minute plants comprise an
important component of the fine-textured sediments which the
annual melting of the Bering Sea floes is sifting down on the
sea bottom.
The nearest locality to Bering Sea from which diatoms have
been found on floe ice is near Cape Wankarema, west of Bering
Strait about 200 miles.
Comparison of the species in the dirt from Bering Sea ice
with those collected from the ice floes near Cape Wankarema
by Kjellman of the Vega expedition and by Nansen during
the drift of the Fram affords some interesting data on the
relationship of floras found on the ice in the Arctic Ocean
and in the Bering Sea. But one species, Coscinodiscus
curvatulus, is common to the Bering Sea diatoms from the ice
near Cape Romanzof, and those collected by Kjellman and
Nansen in the Polar basin; nine species of the Bering Sea ice
flora occur in the Pacific south of Bering Sea; two are found
in the southern part of Bering Sea; one, » Wavicula Fontinalis,
is not recorded from the Pacitie by Mann.*
It is thus seen that the affinity of this ice diatom flora is
very decidedly with that of the Pacific flora to the south and
not at all with that of the Polar sea. This is especially signifi-
cant when it is recalled that the diatom fauna of Cape
Wankarema, which is only about 400 miles from Cape
Romanzof, bears the closest resemblance to the diatom fauna of
the east coast of Greenland. The identity of the large num-
ber of species from the two localities was an important part of
the evidence which led Nansen to formulate the theory of ice
drift across the Polar basin from the Siberian toward the
Greenland coast, which his journey afterwards demonstrated to
be true. The two o samples of mud collected by Nansen from
the floe ice east of Greenland during his expedition to Green
* Albert Mann, Report on the Diatoms of Albatross voyages in the Pacific
Ocean, 1888-1904. Contr. from the U.S. Nat. Herbarium, vol. x, pt. d,
pp. 225-419, pls. 44-54.
E. M. Kindle—Diatomaceous Dust. 179
land in 1889 contained 16 species of diatoms, 12 of which were
known elsewhere only from floes at Cape Wankarema.*
In contrast with this remarkable resemblance between the
Wankarema and the E. Greenland diatom floras which are
separated by the entire breadth of the Arctic Sea, we find
between the Wankarema and Bering Sea floras almost com-
plete nnlikeness, there being but one species common to both.
This sharp contrast between the diatom floras occurring on the
ice to the northwest and to the south of Bering Strait affords
convincing evidence that no definite marine current connects
the two areas which could carry the Wankarema flora south-
ward or the Bering Sea flora northwestward. On the other
hand, the close resemblance of the Bering Sea ice diatoms to
the Pacific flora which is shown by more than nine species
common to the two, indicates a close relationship through
marine currents with the Pacific Ocean.
Dall’s conclusions regarding the movement of water in the
southern part of Bering Sea corresponds with the evidence of
the diatoms in this respect. He states:+ “My own conclusion
from a study of the data is that the general tendency of the
water in bering Sea is to the southward and where deep
enough as in the western part of the sea it forms a tolerably
well defined current.” The ice drift in the vicinity of Cape
Wankarema, on the other hand, was shown by the drift of the
Jeannette to be to the northward or away from Bering Strait.
These opposite tendencies of the currents in the two areas
explain the contrast between the diatoms of Cape Wankarema
and Cape Romanzof.
*H. H. Gran, Diatomaceze from the ice floes and of the Arctic Ocean:
The Norwegian N. Polar Exped., 1893-96, vol. iv, p. 6, 1904.
+ Report U.S. Coast and Geodetic Survey for 1880. Appendix No. 16,
p. 31d.
180 8S. Rk. Williams—Lavoisier and Laplace's Method.
Art. XX.—A_ Modification of Lavoisier and Laplace's
Method of Determining the Linear Coefficient of Expan-
sion; by S. RK. Wiiiiams.
A General Laboratory Method.
Tuer first accurate determinations of the Linear Expansion
Coetlicients of solids were made by Lavoisier and Laplace* in
1782. The rods, whose change in length with temperature
they investigated, were placed in a water-bath with one end
clamped firmly against a rigid wall, while the other end was
fastened to a lever which rotated a telescope about a horizon-
tal axis. The telescope was directed toward a vertical scale
Pie, Ih
and from the deflections the changes in length were determined
as the temperature of the bath was varied from 0° to 100° C.
In the following I wish to describe a simple modification of
Lavoisier and Laplace’s method which overcomes several difli-
culties encountered in that of the original as well as in the
numerous devices now used for this experiment.
Figure 1 shows the apparatus as used in the laboratory, and
fioure 2 shows it schematically. The steam-jacket, A, encloses
the rod, R, whose change in length is to be studied.
* Lavoisier and Laplace, Bot. Traite de Physique, vol. i, p. 151.
S. R. Williams—Lavoisier and Laplace’s Method. 181
As will be noted, the essential difference between this
arrangement and that of Lavoisier and Laplace is that the
steam- jacket and rod are here arranged in a vertical position.
A small rubber band at J holds the tube, A, lightly against
the V opening at Y. By means of corks in the ends of the
tube, particularly the lower one, the steam-jacket is supported
on the rod, R, which in turn rests on its end in a depression in
K. This insures that the lower end of the rod will always
Hie. 2.
LLLLLLLLL ELL LLL LLL LLL
LLLLLL LLL
LLL LL LLL
CMU
remain in a ae position without the necessity of clamping it,
and prevents the tube from creeping due to its own expansion.
In some five or six devices for measuring the linear coefficients
in which the steam-jacket rested in a horizontal position in Y’s,
as in figure 3, I have found that the tube creeping carried the
bar along with it; this is usually overlooked by the student
and the results obtained are very discordant.
K is a thin strip of brass with a small depression in which
the lower end of the rod rests. In one type of expansion
182. S. R&R. Williams—Lavoisier and Laplace's Method.
apparatus this block, against which one end of the rod was
placed, was about two inches long, and its expansion from the
heat of the rod was quite appreciable. H is an opening in the
side-of the tube with a cork through which the thermometer,
T, is thrust. The base, B, was made from a plank 2x10 24
inches, and the back support, V, was 2X8 X81 inches. This
stand was made heavy in order that any heating effects from
the steam-jacket would not warp or distort it during the experi-
ment. In figure 8 is shown the usual support for the steam-
Je, Bp
MSS S55 5)
di a
OL hochhnlonlbcbcbababrbd bbb LLLoLeeLLLIALLLAREA LEE LE DEES
jacket, in a horizontal position, which is either of thin boards
or a metal bar. <A slight pressure at C will change the read-
ings altogether, or if the upper side of the base, whether wood
or metal, is at a different temperature from the lower the same
results will occur. The optical lever for measuring changes in
length has been adhered to because it admits of great accuracy
and yet is simple.
The method of focusing the cross wires of two microscopes
on the ends of the bar and then by means of micrometer eye-
pieces measuring the changes in length is nsed by the Inter-
national Bureau of Weights and Measures, and is very accurate,
but for high school laboratories it is too elaborate, and for the
average college is rather expensive. None of the common
methods, as the electric contact, the vernier micrometer and
the wooden lever, are as precise as the two mentioned above.
The vertical position of the steam-jacket and rod makes the
use of the optical lever a convenient one, since the back, V,
can be made the same height as the rod, and with the mirror,
M, on a tripod bridging across from V to kh, the telescope and
scale, S, can be put in a convenient position for observations.
I and O are the openings for the passage of steam through
the steam-jacket. In the general laboratory we have taken the
length of the bar at room temperature and then again at the
temperature of steam, but the apparatus may be very easily
adapted to the circulation of water in the steam-jacket and so
the lengths for intermediate temperatures may be obtained.
This apparatus has been in use for two years in the general
laboratory, and { have found that the students have reported
very concordant results. Its simplicity makes its construction
possible with a very limited supply of tools and means.
Physics Laboratory, Oberlin College, May 12, 1909.
Cook—New Proboscidean from the Lower Miocene. 183
Art. XXI—A New Proboscidean from the Lower Miocene
of Nebraska ; by Harorp J AMEs Cook.
*Gomphotherium conodon sp. nov.
In the collections of the writer are two broken teeth (No.
HC 176) found in the summer of 1906 in the lower part of the
Upper Harrison beds, near Agate, Sioux County, Nebraska.
Although averse to founding new species on fragmentary
material, the type here represented seems quite important, and
as the Upper Harrison beds have been vigorously searched by
Rie 1.
several parties during the past three years and no other
evidence of this unexpected form has been secured, a descrip-
tion is here given.
The teeth are unwor n, and may be a part of the milk denti-
tion, but are quite differ ent from any described species. They
are ‘simple bunodont teeth, with a very heavy crinkled cin-
gulum, which tends to develop into cusps as in other probos-
cideans. Though apparently somewhat more robust, the teeth
are essentially more simple than those of Palwomastodon.
They have only a slight roughness on the sides of the
cusps, where Palwomastodon las a distinct tendency toward
a crest. The tubercles or cusps are relatively low and blunt,
much like those of the Eocene proboscideans. The enamel is
very much thinner than in any known American type.
* Gomphotherium Burmeister, 1837 = Tetrabelodon Cope, 1884.
184. Cock—New Proboscidean from the Lower Miocene.
Although the specimen is provisionally referred to the
genus Gomphotherium, it probably represents an undescribed
genus, and may be a persistent primitive type.
It does not agree with any known type of Antelodon in that
the cingulum is very much heavier and crinkled, developing
distinct cusps. Though it is impossible to state the exact
molar tooth-pattern, owing to the fragmentary condition of
the specimen, one tooth shows a particularly well-developed
cusp on the cingulum, about one-fourth of an inch in height.
As it is an unexpected type from these beds, a word as to
its occurrence may be in order. There can be no question as
to its belonging to the Upper Harrison beds, asa part of one
tooth was found in the matrix. In the lhght of the latest dis-
coveries in these beds, they appear to represent a phase of the
Lower Miocene. |
The writer is indebted to Prof. Charles Schuchert and Prof.
RK. 8. Lull of Yale, also Prof. H. F. Osborn and Dro Wow:
Matthew of the American Museum of Natural History, for
assistance rendered in the study of this type.
American Museum of Natural History,
New York, Dec. 12, 1908.
Ford, Ward and Pogue—Minerai Notes. 185
Arr. XXIL.—Wineral Notes from the Mineralogical Labo-
ratory of the Sheffield Scientific School of Yale University.
1. Calamine Crystals from the Organ Mts., Donna Anna
Co., V. M.; by W. E. Forp and Freeman Warp.
Durine the past year several specimens of calamine from
the Organ Mts., Donna Anna Co., New Mexico, have been
acquired by the Brush Mineral Collection. These specimens
show distinct and separate crystals of unusual size and quality
hres 1 Gace
for calamine, resembling in appearance and character the
erystals from Altenberg, Belgium. Because of the rarity of
such occurrences of the mineral it was considered worth while
to measure and figure these crystals and to eall attention to the
occurrence by a note. Unexpectedly the study revealed the
presence of a form apparently new to the species.
The crystals are clear and colorless with a tabular develop-
ment parallel to 6 (010), and average about 1™ by 5™ for
their largest dimensions. The forms identified upon them
were as follows : 6(010), c(001), m(110), 7 (407)*, s(101), ¢(301),
Am. Jour. Sct.—FourtH Series, Vou. XXVIII, No. 164.—Aveusrt, 1909.
13
186 Ford, Ward and Pogue—Mineral Notes.
e (011), 7(031), v(121). The crystals were all attached and no
faces terminating the antilogous poles were observed. They
were usually developed as shown in figure 1, while the pyramid
v, the brachydome 2 and the new macredome 7, were only
observed on a few erystals, and then but as small truncations,
as is shown in figure 2. The new form (407) occurred as very
small but definite-shaped faces, which did not yield very sharp
reflections. No other simple indices would satisfy the angle
measured, and it is thought, therefore, that the identity of
a ve
a
[ih NES
the form is reasonably well established. The measured angle
of ¢(001)az (407) was 19°+, the calculated angle being
VOT 2D: ?
2. Calcite Crystals from Kelly’s Island, Lake Erie ;* by W. E.
Forp and J. L. Pocus.
recently, through Mr. Lazard Cahn, the Brush Collection
received some calcite crystals from Kelly’s Island, Lake Erie,
which were remarkable in that the prominent form upon them
was the rare pyramid, y(8°8-16°3). The pyramid exists on the
crystals alone with the exception of a rounded rhombohedral
termination which was assumed to be ¢(0112). The measured
angles which identified the pyramid form were, (8°8°16°3) A (8°8°
*The form y(8°8'16°3) has been noted as a prominent form on crystals
from Bellevue, Ohio. Farrington and Tillotson, Field Columbian Museum,
Geol. Series, ili, No. 7, 144, 1908.
Ford, Ward and Pogue—Mineral Notes. 187
16°3)= 24° 42’ and 24° 48’ agreeing closely with the calculated
value of 24° 46’. This pyramid was first noted by vom Rath*
on crystals from Andreasberg in the Harz ;and has been noted
on erystals from Union Springs, Cayuga County, NBR) Dy:
Penfield and Ford,+ but never so far, as the writers know, has
it been found so largely and simply developed, as in this
instance. The crystals are honey-yellow in color, and average
from 3 to 4™-in length and from 1 to 1°5™ in greatest
diameter.
3. Crystals of Datolite from Bergen Hill, N. J.; by W. E.
Forp and J. L. PoGue.
A short time ago Prof. E. 8. Dana received from Mr. James
G. Manchester of New York City a small suite of unusally
pertect and symmetrical datolite crystals, which being shown
to the present writers seemed worthy of a brief description.
They were found lying loose in sandy material at the bottom
of the open cut which is at present bemg put through the trap
ridge at Bergen Hill by the Erie railroad. Most of the erys-
tals were completely and symmetrically developed, and showed
no evidence of previous attachment to other minerals or a rock
surface. In one specimen the small crystals of datolite were
seen lying in the angles between interpenetrating rhombohe-
drons of calcite, and in another they were associated with an
asbestiform mineral and minute crystals of apophyllite. The
crystals were all of them small, the largest of the suite shown
in its true proportion and development in figure 4 being 8™™
in its greatest diameter. Many of the crystals were much
smaller. They are colorless, perfectly transparent, and their
faces have a brilliant luster. But of chief interest is the
almost ideally symmetrical development which they possess, a
thing of considerable rarity among datolite crystals. The
forms identified, all of which are common, were as follows:
a(100), ¢(001), m GENO); mm. (O11)) Wi(t14), A (112), A Glas
Mineralogical Laboratory of the Sheffield Scientific School of
Yale University, New Haven, Conn., July 1, 1909.
*Pogg. Annalen, exxxii, p. 521, 1867. + This Journal, x, 237, 1900.
188 Soventific Intelligence.
SOTHENTIEFIC INDTERLVG EN © Re
I. GEOLOGY.
1.. The Tidal and Other Problems— Contributions to Cos-
mogony and the Fundamental Problems of Geology ; by T. C.
CHAMBERLIN, FI’. R. Moutton, C. 8. Sricuter, W. D. MacMirxian,
ArtTHuUR C. Lunnand Juius St1EcLitz. Pp. 264. Washington,
D. C., 1909. (Published by the Carnegie Institution of Wash-
ington.)—In the department of science to which they relate, this
series of papers will doubtless take rank among the most import-
ant ever published. Not a little of their value is due to the fact
that the plans of the investigations have been controlled by a
leading geologist on the one hand and a master of celestial
mechanics on the other, while many of the detailed problems
have been handled by men who were specialists in the respective
lines of research involved. By this collaboration the premises
and results have been checked with the known details of earth
history and celestial relations, and a greater degree of reliance
reached in regard to the methods of investigation which were
employed. Within the limits of this review, only the more
important conclusions can be given, and itis hoped that the result
will be to produce a wider study of the volume itself. The first
large subject treated under six papers is that of the tidal problem
with its bearings on the former rate of the earth’s rotation, its
influence on the modes of crustal deformation, the initial relations
of the earth and moon, and also the problem of the origin of
binary stars through fission.
The opening paper is by Chamberlin, and in an introductory
portion he gives a synopsis of previous work, followed by a redis-
cussion of tidal phenomena. The geological evidences are also
considered, this topic being treated along the lines followed in
Chamberlin and Salisbury’s geology. His conclusion is that :
“'The application of the most radical and the most rigorous
method of estimating the frictional value of the present water-
tides, a method which brings to bear practically all the friction
of these tides as a retardative agency, irrespective of their
positions or directions of motion, seems to show that they have
only a negligible effect on the earth’s rotation.
“From the best available evidence I conclude that the tides of
the lithosphere are chiefly elastic strains and have little retarda-
tive value, while the tides of the atmosphere are too small to be
measured.
“The accelerative influences seem to be also negligible, so far
as geological applications are concerned.
‘““In close accord with these deductions, the geological evidences
indicate that there has been no such change in the rate of the
wees:
7 Ped
Geology. 189
earth’s rotation during its known history as to require it to be
seriously considered in the study of the earth’s deformations ”
(p. 59).
The quantitative portions of the paper rest upon one on “ Zhe
Rotation Period of a Heterogeneous Spheroid,” by C. 8. Slichter,
and another “ On the Loss of Energy by Friction of the Tides,”
by William D. MacMillan. ‘The latter uses the formule employed
by engineers for the loss of head due to friction and viscosity,
and applies them to the ocean. His conclusion is that the day
would be lengthened by one second in about 500,000 years.
Eyen if this figure be in error tenfold or a hundredfold it is still
in great contrast with the conclusion of Adams in the middle of
the last century, that the earth was losing time at the rate of 22
seconds per century, a figure raised to 23-4 seconds by Darwin and
lowered to 8°3 seconds by Newcomb.
As Chamberlin points out, these figures have been derived from
a secular acceleration of the moon’s mean motion, and until a per-
fect lunar theory is developed such a small irregularity cannot
safely be used for the foundation of a superstructure reaching
backward tens of millions of years. It is seen that MacMillan’s
work supports on an entirely independent line of evidence the
previous conclusion that no appreciable change in the rate of
earth rotation has occurred during the intervals of time assigned
by geologists for the portion of earth history recorded in the
sedimentary formations.
The next paper is by F. Rh. Moulton, “ On Certain Relations
among the Possible Changes in the Motions of Mutually Attract-
ing Spheres when Disturbed by Tidal Interactions.” ‘This deals
_ with the general problem of tidal evolution with applications to
the earth-moon system. The author first shows that less critical
minds than Darwin’s have drawn more definite conclusions from
Darwin’s work than he himself drew. He next states:
“In questions of cosmogony, where immense intervals of time
are involved, the problem of tidal evolution is obviously one of
great importance, unless it shall some time be shown that it is
not a sensibly efficient factor. The two most obvious methods
of determining its efficiency are by direct attacks from the
mathematical standpoint, or by comparing its certain implica-
tions with as many facts given by observation as possible. The
first is mainly the method of Darwin, and he has written what
will certainly always be an extremely important chapter in the
question when considered in the broadest possible way.’ aries “8
“The second method, that of comparing the positive implica-
tions of the tidal theory with observed facts in as extended a
way as possible, is, broadly speaking, that adopted in this paper ”
(p. 83).
At the end of the paper Moulton gives a summary, from which
the following abstracts are taken :
mat He object of this investigation has been to examine the
theory of tidal evolution in order to find out, if possible, not
190 Scientific Intelligence.
what might take place under certain assumed conditions, but how
important this process has been in the actual development of our
system. ‘The aim has been to avoid, as far as possible, assump-
tions regarding the uncertain factors depending upon the physi-
cal conditions of the bodies involved. In order to compare the
theory with the actual facts the various methods of testing it
have been carried to quantitative results.” * * *
“One of the conclusions reached by Darwin was that it is
probable that the earth and moon have developed from an
original mass by fission. One critical test of this hypothesis is
the determination of the smallest distance at which the bodies
could have revolved around each other consistently with the
present moment of momentum and energy. This test has been
worked out quantitatively, first with the problem simplified so
that the conclusions are absolutely certain under the hypotheses ;
then the effects of various modifying conditions, which seem
more or less probable, have been examined, one after another,
and their influence upon the final result determined” (p. 127).
It is found that, under the simplified conditions:
“The month has always been increasing and that it cannot
pass beyond 47:7 of our present days, at which period the month
and day will be egual and the system move as a rigid body.
There is no way of telling by this investigation how long a time
will be required for the system to reach that state. But it is a
more interesting fact that the month can never have been less
than 4°93 of our present hours, this being the period of revolu-
tion when the distance from the center of the earth to the center
of the moon was 9,194 miles. Consequently we must suppose
that when the moon broke off from the earth it was at this dis-
tance from it, or 5,236 miles from its present surface. Or, includ-
ing the radius of the moon and supposing that both the earth
and moon were of the same density and shape as at present, the
distance from the surface of one body to the surface of the other
was immediately after fission 4,155 miles. Since this result is
altogether incompatible with the obvious implications of the
fission theory; we must either abandon the theory or show that
this number would be very largely reduced by including the
effects of the neglected factors. Consequently we examine the
effects of various neglected conditions and influences” (pp. 128,
129).
As a result
“It is seen that the one factor which makes the moon’s initial
distance less than that found in the first computation is not only
of no particular consequence, but also that it is less than some of
the factors which increase it. Using all those factors whose
effects have been computed when they have been supposed to act
separately, and supposing that they would be essentially the same
when acting jointly, we find that the smallest possible distance of
the moon compatible with present conditions is 9,241 miles.”
nctpaitemnantinttteliiiiss
Geology. 191
*¢ As a concession to the theory, we may assume that the earth
and moon have separated by fission so that their periods of rota-
tion and revolution are precisely equal, and then inquire whether
the present system could develop from it. If the original orbit
were exactly circular the orbit would always remain circular.
Since the moon’s orbit now has considerable eccentricity it foliows
that we must assume that the orbit immediately after separation
was somewhat eccentric. But since the rotations would be
sensibly uniform while the revolution would be such as to fulfil
the law of areas, there would be relative motion of the various
parts and therefore tidal evolution. The question whether this
friction would drive the moon farther from the earth or bring it
back and precipitate it again upon the earth is treated in section
X, and itis found there, under the assumption that the loss of
energy is proportional to the square of the tide-raising force and
the square of the velocity of the tide along the surface of the
earth, that the tides would bring the moon again to the earth.
Thus, unless some of the neglected factors can offset this result, the
direct implications of the theory destroy it, and it may be noted
here that these remarks apply with equal force to the hypothesis
that the binary stars have originated by fission and that their
present distances from each other and the eccentricities of their
orbits are a result of tidal friction ” (pp. 130, 131).
“It is well known that a comparison of ancient and modern
eclipses shows that the moon has an acceleration in longitude of
about 4” per century which is not explained by perturbations.
Let us assume that this is due to tidal friction and is the measure
of it at the present time. At this rate it will take over 30,000,000
years for the moon to gain one revolution. Consequently we see
without any computation that it must have been an extremely
long time in the past when its period was a small fraction of its
present period.
“'The problem was treated in section XV, and it was found there
that, if the physical condition of the earth has been essentially
constant, the length of the day was 20 of our present hours, and
of the month 24 of our present days, not less than 220,000,000,000
years ago. It is extremely improbable that the neglected factors,
such as the eccentricity of the moon’s orbit, could change these
figures enough to be of any consequence. This remarkable
result has the great merit of resting upon but few assumptions
and in depending for its quantitative character upon the actual
observations. If it is accepted as being correct as to its general
order, it shows that tidal evolution has not affected the rotation
of the earth much in the period during which the earth has here-.
tofore been supposed to have existed even by those who have
been most extravagant in their demands for time. And if one
does not accept these results as to their general quantitative
order, he faces the embarrassing problem of bringing his ideas
into harmony with the observations” (p. 132).
“In a word, the quantitative results obtained in this paper are
on the whole strongly adverse to the theory that the earth and
192 Scientific Intelligence.
moon have developed by fission from an original mass, and that
tidal friction has been an important factor in their evolution.
Indeed, they are so uniformly contradictory to its implications
as to bring it into serious question, if not to compel us to cease
to consider it as even a possibility ” (p. 133). |
Moulton’s results, based mostly upon the fundamental equa-
tions of moment of momentum and energy of the earth-moon
system, are thus seen to be an independent proof in harmony with
the two preceding, that no changes of importance in the rate of
earth rotation have taken place within the period of known earth
history, going, however, still further, and pointing to their always
having been separate masses.
The next paper consists of ‘* Motes on the Possibility of Hission
of a Contracting Rotating Fluid Mass,” by F. R. Moulton. In
the summary at the end of the paper it is stated : |
“The problem under consideration is that of the fission of
celestial bodies because of rapid rotation when they are not dis-
turbed by important external forces. The attack is made through
well-known results concerning the figures of equilibrium and
conditions as to stability of rotating homogeneous incompressible
fluids. It is recalled that for slow rotation a nearly spherical
oblate spheroid is a stable form of equilibrium ; that for greater
rates of rotation the corresponding figure is more oblate ; that
when the eccentricity of a meridian section becomes 0°813 the
figure loses its stability and at this point a stable line of three-
axis ellipsoids branches ; that when the longest axis of the ellip-
soid becomes about three times the axis of rotation a new series,
known as the pear-shaped figures (or better, perhaps, the cucum-
ber-shaped figures) branches, and that before this point 1s reached
there is no possibility of fission. We are almost entirely ignorant
as to what may happen after this point 1s passed, and it must be
remembered that it has not been proved that in any-case fission
into two stable bodies is possible.
“The celestial bodies differ from those just considered in two
important respects. In the first place their densities increase
toward their centers. For a given rate of rotation and mean
density this central condensation makes them more nearly spheri-
cal, as is shown both by theory and by comparison of the
observed figures of the planets with the computed forms of
corresponding homogeneous masses. In the case of Saturn, for
example, the eccentricity computed on the hypothesis of homo-
geneity is 0°607 while the observed value is only 0°409. It seems
certain that this central condensation tends toward stability. The
second important difference between the ideal homogeneous
incompressible fluids and the celestial bodies is that the latter are
compressible. This latter factor, at least under certain circum-
stances, tends toward instability.
“The opposing quantitative effects of central density and com-
pressibility undoubtedly differ greatly in different masses and
can not be easily determined in any case. However, if we may
ality heey”
Geology. 193
assume that they approximately offset each other, we may reach
some conclusion respecting the possibility of the fission of the
actual celestial bodies by discussing the corresponding homo-
geneous incompressible body. This is the assumption adopted
here, but, because of its uncertainty, in the applications to the
solar system, where it turns out fission is impossible, all approxi-
mations are made so as to favor fission, and it is assumed that in
the actual bodies fission may be immanent long before it is
possibie in the homogeneous ones. ‘These safeguards and simpli-
fications are possible and easy because it is a negative Tesult
which is reached ” (p. 158).
“ For the applications we assume that an actual celestial body
will not be in danger of fission until the corresponding homo-
geneous incompressible body arrives at the state where the
Jacobian ellipsoids branch. ‘The density at this stage is less
than one-fourth that at which the pear-shaped figures branch,
and actual fission in the homogeneous bodies is certainly beyond
this form, if indeed fission into only two bodies is ever possible.
With this very conservative assumption we proceed to some cal-
culations.
“(1) We find that the sun can not arrive at this critical stage
until its mean density shall have exceeded 307 X10” on the water
standard. ‘This corresponds to an equatorial diameter of the sun
of about 22 miles.
(2) We find that the sun can not become so oblate as Saturn
is now until its mean density shall have exceeded 14810" on
the water standard. ‘This corresponds to an equatorial diameter
of the sun of about 75 miles.
‘Since even the latter density is impossibly great, we conclude
that the sun will never become so oblate as Saturn is now, and
that it will always be more stable than Saturn is now.
(3) We find that Saturn can not arrive at the critical stage at
which the Jacobian ellipsoids branch until its mean density shall
have become 21 times that of water. This corresponds to a polar
diameter of 16,500 miles and an equatorial diameter of 28,400
miles. We conclude because of the great density demanded that
Saturn will never suffer fission.
“(4) We assume that the earth and moon were once one mass
and get their original moment of momentum from its present
value. In computing it, however, we make certain approxima-
tions so as to get it too large and thus favor the conclusion of
fission, then we add to it the maximum amount the sun’s tides
can have taken from the earth, and finally we add 25 per cent for
fear there may be some unknown sensible factors omitted. Then
we find that this hypothetical earth-moon mass could not get even
to the critical point where the Jacobian ellipsoids branch until
its mean density became 215 times that of water, or about 40
times the present mean density of the earth and moon. It would
not become even so oblate as Saturn is now until its density had
become 10°4 times that of water. Therefore we conclude that
194 Seientifie Intelligence.
the hypothetical case was false, and that the moon has not origi-
nated by fission from the earth in this way.
‘¢(5) In applications to the binary stars the results are less defi-
nite because of the meager data regarding these systems. But
assuming that fission in stars will occur when the Jacobian ellip-
soids branch in the corresponding homogeneous masses, we find
for the density o in terms of water at the time of fission when
the two stars are of equal mass
0°016
0
where P must be expressed in mean solar days. Even though
fission should not occur until the density is ten times this amount
(which, if true, makes the evidence against fission in the solar
system much stronger), all visual binaries of two approximately
equal masses must have separated, if they have originated by
fission, while they were yet in a nebulous state. The results are
of the same order so long as the disparity in the two masses of a
binary is not very great, and this probably includes all of the
visual binaries.
“(6) Certain formulas, not connected with the question of fis-
sion, were developed for binary systems” * * * *
“The results obtained by the computations given are quite
adverse to the fission theory, in general, except if it is applied to
masses in the nebulous state, and seem practically conclusive
against it so far as the. solar system 1s concerned, either in the
future or past. Perhaps the hypothesis that stars are simply
condensed nebulas, which has been stimulated by a century of
belief in the Laplacian theory, should now be accepted with
much greater reserve than formerly. Up to the present we have
made it the basis not only for work in dynamical cosmogony but
also in classifying the stars. It may be the time is ripe for a
serious attempt to see if the opposite hypothesis of the disinte-
gration of matter—because of enormous subatomic energies, which
perhaps are released in the extremes of temperature and pressure
existing in the interior of suns, and of its dispersion in space
along coronal streamers or otherwise—can not be made to satisfy
equally well all known phenomena. The existence of such a
definitely formulated hypothesis would have a very salutary
effect in the interpretation of the results of astronomical obser-
vations. We should then more readily reach what is probably a
more nearly correct conclusion, viz., that both aggregation and
dispersion of matter under ‘certain conditions are important
modes of evolution, and that possibly together they lead in some
way to approximate cycles of an extent in time and space so far
not contemplated ” (pp. 159, 160).
In the next paper on “ The Bearing of Molecular Activity on
Spontaneous Fission in Gaseous Spheroids,” T. C. Chamberlin
considers from the standpoint of the moment of momentum the
postulation of a shrinking gaseous spheroid reaching a critical
stage at which centripetal and centrifugal forces balance each
ee etna
Geology. iyo
other in the equatorial zone. The prowlen to be solved is whether
bodily separation of a portion of the spheroid would tend to take
place, or whether it would shed material molecule by molecule.
A discussion of the several outer zones of gas is given following
the lines pursued by G. Johnston Stoney, “and it is shown that
molecules in the outer zone which reach the critical parabolic
velocity will be directed forward owing to the velocity of rota-
tion being added to the velocity of impact from behind. A cer-
tain per cent will further be given larger orbits owing to impact
from below, and will thus become minute and independent satel-
lites. In conclusion, Chamberlin states :
“Those molecules which make elliptical flights and return to
the spheroid without collision carry back whatever moment of
momentum they took out, but those thrown into permanent orbits
retain, as a rule, not only what they took out but also the addi-
tional moment of momentum gained from the collisions which
gave these free orbits. It follows that every molecule that goes
into a free orbit takes a disproportionate amount of the moment
of momentum of the spheroid and thus reduces its Boron, or
else retards its increase of rotation, to that extent” * *
“From the nature of the case, I entertain, with a the
view that the separation must take place molecule by molecule,
and it seems to me inevitable that these molecules must go into
orbits each carrying an excess of momentum at the expense of
the spheroid, and hence that the critical stage of exact balance
between the centrifugal and centripetal factors of the spheroid
is never reached. If so, bodily separation is excluded by the
conditions of the case.
“The conviction that such rotating gaseous spheroids must shed
portions of their matter molecule by molecule, if they do so at
all, has long been held by students of the subject, but I am not
aware that the loss of moment of momentum from the spheroid
has been urged as a reason why the critical state prerequisite to
bodily separation may not be attainable ” (p. 167).
The result of these last two papers goes to show on independ-
ent lines that celestial bodies cannot suffer bodily disruption
owing to cooling and shrinking of their own mass attended by
acceleration of rotation.
The following paper is on “ Geophysical Theory under the
Planetesimal Hypothesis,” by Arthur C. Lunn :
“This paper is devoted mainly to a quantitative study of that
portion of the earth’s internal energy which is supposed to have
been derived from the mechanical energy of a primitive system
of planetesimals, of its transformation into thermal form during
the epoch of accretion, and its subsequent redistribution by con-
duction ” (p. 171).
It occupies sixty pages, and brings out important mathemati-
cal relations, but as it involves details regarding centrospheric
conditions consequent upon one hypothesis of earth origin and is
not so evidently a test of hypothesis, a detailed discussion may be
omitted from the present review.
196 Scientific Intelligence.
The final paper is on “ Zhe Relations of Equilibrium between
the Carbon Dioxide of the Atmosphere and the Calcium Sul--
phate, Calcium Carbonate, and Calcium Bicarbonate of Water
Solutions in Contact with it,” by Julius Stieglitz. The purpose
of the paper is to obtain a relation, if possible, between the
chemical composition of gypsum deposits and the carbon dioxide
of the atmosphere at the time of formation. The considerations
developed make it desirable to examine such deposits of gypsum
very carefully and exactly for even very small quantities of cal-
cium carbonate. SB
2. Second Appendiz« to the Sixth Edition of Dana’s System of
Mineralogy ; by Epwarp 8. Dana and Wirtiam E. Forp.
Pp. xi, 114. New York, 1909 (John Wiley & Sons).—Ten years
have passed since the publication of the First Appendix to the
Sixth Edition of Dana’s Mineralogy, and during this time a very
large amount has been added to the literature dealing with
mineral species. This second appendix, now issued, gives a con-
cise summary of this lhterature with full descriptions of all the
well-established new species. Of these new species there
are some sixty out of about two hundred new names, the
remainder having been given to varieties and to imperfectly
described minerals. ‘The larger part of the labor on this appendix
has been done by Professor Ford, who took up the work, when
the senior editor was compelled to relinquish it, and carried it
through to completion.
3. Sketch of the Mineral Resources of India; by T. H. Hot-
LAND, Director, Geological Survey of India. Pp. xi, 86, with two
maps. Calcutta, 1908.—Many interesting points are brought out
in this summary. It is noted that the total value of mineral
production in India (for 1906) was £6,313,000 ; of this gold and
coal made up two-thirds. Other prominent products in order of
importance are: petroleum, manganese, salt, saltpeter and mica.
The value of the ruby, sapphire and spinel mined was about
£100,000 and of jadeite £64,400. India has now lost by foreign
competition the prominent place she once held in her metallurgical
industries, of iron, copper and brass, and chemical industries of
borax, niter, alum, blue vitriol, copperas, etc. The rapid spread
of railways, however, gives reason to hope that the increased -
local demand may restore something of the ancient prosperity in
these lines. 3
4, Igneous Rocks: Composition, Texture and Classification,
Description and Occurrence; by JosErH P. Ippines. In two
volumes. Volume l. Pp. xi, 464, 3 plates. New York, 1909
(John Wiley & Sons).—This important work has recently been
issued ; a notice is deferred until a later number.
OBITUARY.
Professor Simon Newcoms, the astronomer, died in Washington
on July 11 in his seventy-fifth year. A notice is deferred until a
later number. |
ir. Cyrus Adler, | eee 8 RS
| pean U. S. Nat. Museum.
x XXVIIL oe | SEPTEMBER, 1909.
TF
' Established by BENJAMIN SILLIMAN in 1818.
= AMERICAN
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VOL. XXVIII-[WHOLE NUMBER, CLXXVIIL
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IMPORTANT NOTICE
The past month has been a busy one and has brought us many consign-
ments covering practically the whole world. They cover the finest grades
of crystallized minerals, together with many rare and almost unattainable
specimens and rich ores. Among these consignments were two old collec-
tions full of specimens from exhausted localities. These specimens must be
seen to be appreciated.
NEW ARRIVALS
The new minerals Calciovolborthite, crystallized, from Telluride, Colo.;
Vanadinite, all colors, from Kelly, N. Mexico; Limonite after pyrite, large
and small cubes, Albemarle Co., Va.; Smithsonite, Kelly, N. Mexico; Tel-
lurium, Sylvanite, Calaverite, Free Gold in quartz, Carnotite, Topaz,
Amethyst, Amazonstone, Vivianite, all from Colo.; Tourmaline emerald
Green, Gem Crystals, flawless, from a new find in the southern part of
California.
A large consignment from well known localities in Saxony and Bohemia.
Some of these are extremely rare and fine.
PROFESSORS COLLECTION
We have still some of the finest specimens left of the Professors Col-
lection, mentioned in the August number of this Journal.
LATEST DISCOVERY
We have just received from Paris a small consignment of reconstructed
pink Topaz and pink Sapphires, very rich in color and brilliancy; also a
new gem, dioptase, cut cabachon and round, from French Congo.
We have all known precious and semi-precious stones ; will send box on
approval by request ; further particulars cheerfully furnished.
A. H. PETEREIT,
81—83 Fulton Street, New York City.
a. it as Vedi Sy
dP e623
AMERICAN JOURNAL OF SCIENCE
Pee U RTH SERIES. |]
Arr. XXIU1—TZhe Physiography of the Central Andes:
I. The Maritvme Andes ; by Isataa BowMAN.
I. Tut Maritime ANDEs.
Coastal Features.
Amone the long list of features which the western part of
South America has in common with the western part of North
America, none is perhaps more striking ‘than the recent
changes of level for which both are, from the human stand-
point, unfortunately too well characterized. The recent
destruction of Valparaiso occurred too soon after the San
Francisco catastrophe for us to appreciate how appalling it
actually was ; while the lack of early newspaper reports from
South America in years gone by no less than to-day has kept
us from having even a reasonable appreciation of the frequency
and destructiveness of the great earthquakes that virtually
destroyed Arequipa in 1860, and Iquique, Arica, and Pisagua
in 1877
The entire western seaboard of South America supplies evi-
dence of the magnitude of the crustal disturbances that the
region has suffered in the past and is suffering to-day. The
great height attributed to recent uplifts by Darwin has
become a ‘point of classic dispute, but whether his conclusions
are accepted or rejected for the locality in question, there are
elsewhere indubitable evidences of uplifts as great and import-
ant as those he concluded had occurred in Chile. The earth’s
crust is here unstable to a high degree, and constant changes,
large and small, have aggregated an uplift among the most
protound of those exhibited on the earth to- day. “The eross-
section, figure 1, represents the astonishingly abrupt transition
Am. Jour. Sci.—Fourts Series, Vou. XXVIII, No. 165.—SEpremBer, 1909.
14
198 JL. Bowman—Physiography of the Central Andes.
from lofty tableland to abysmal ocean depth that is character-
istic of the entire coast. It represents conditions along the
coast of northern Chile in the vicinity of Taltal, where the
Andes, attaining a height of over 16,000 feet, fall off to the
Enc. ale
SALAR DE SALAR DE SALAR DEL Rio
PUNTA NEGRA ARIZARO PASTOGRANDE aes VALLEY!
cos CRUCHULAL : y
PACIFIC OCEAN
COASTAL PROFILE, CHILE, LATITUDE 24° 30's.
Scale; Horizontal, 1 ene ={50 kilometers, Verticalxs. &
enormous depth below sea level of over 25,000 feet, a total
descent of over 40,000 feet in 175 miles. Of this descent,
32,600 feet is accomplished in 75 miles. From the north-
Fig. 2
Fie. 2. Coastal Terrace at Payta, Peru.
western coast of Peru southward to Concepcion, in southern
Chile, the 4,000-meter submarine contour is never more than
125 miles from the coast and generally less than half that dis-
I. Bowman—Physiography of the Central Andes. 199
tance away. We have here one of the great planes along
which a major segment of the earth’s crust is under going
adjustment, the line of movement being oftentimes indicated
by earthquakes and the amount by recently uplifted shore
forms of unmistakable identity.
At the port of Payta in northwestern Peru one may obtain
a very clear notion of the recency of the crustal movements
that have affected the land thereabout. On the left of figure 2
Fie. 3.
Fic. 3. Coastal Terraces at Mcllendo, Peru.
a sea terrace only a few feet above sea level may be observed.
Jt runs up each of the reéntrants and rounds all the spurs with
even contour. Its materials are of exactly the same sort as
those in the existing beach below it and the shells occurring in
it are likewise identically like those of the present shore. It
appears to have been formed but yesterday,so fresh are its
details of structure and relief. Just outside the port, at the
Punta de Foca, are wider terraces cut into the rock as well as
the soft sands and gravels that overlie the rock. It is now
being scored by the intermittent streams dependent on the
seven-year rains, and is being cut off on the seaward side by
wave action. Its smooth upper surface in the interstream
areas is still strewn with wave-rolled material ; and the beach,
except for the work of the scoring streams, seems as in the
previous case to have been exposed but yesterday.
200 L, Bowman—Physiography of the Central Andes.
The most extraordinary development of wave-cut terraces
observed a ere those at the port of Mollendo, in southern
Peru, fig. 8. The terraces increase in height from the northern
part of the Peruvian coast and reach a splendid development
at this point. ‘They are visible at sea as great, long, gently-
sloping, rock benches of huge size. Oppor tunity was afforded
for the more detailed examination of their upper surfaces than
was possible in the preceding cases (Payta, Lomas, Pisco, Eten,
ete.), and it was found that evidence for their formation by the
sea and subsequent uplift to a height of at least 1,500 feet is
conclusive. At an elevation of 800 feet, a clay bank was
observed in the side of a gorge, or quebrada, i in which in a
natural position were found recent shells of the same sort as
those now found in the present beach. It appears that, after
the formation of the terrace at this level and its partial dissec-
tion as the result of elevation, it was again submerged long
enough and deep enough for the formation of the clay and
the deposition of the shells. A second uplitt then brought
the whole above water and it is this movement that is continu-
ing to-day. About the inner margin of the terraces are coves
like those now seen at many places on the present strand-line
or but a little above it. They are not so clearly distinguish-
able as the latter because of the partial filling or obliteration
that they have suffered, but their characteristic outlines are
still to be made out with certainty. The whole aspect of the
terraces with their regular outlines is in striking contrast to
the highly irregular forms of the mountain side above them
where the planing action of the sea is not expressed.
It would be a repetition of the foregoing descriptions to
note the individual features of the different terraces observed
along the coast farther south; and these have been described
to some extent in the accompanying list of papers,* and their
description hereis unnecessary. At Iquique, at Tocopilla, Anto-
fagasta, and elsewhere, they are developed as clearly as in the
pr eceding cases. In each ease the topographic outlines are as
clear an index of their manner of formation as are the shells
found upon the terraces at Paytaand Mollendo. Though these
shells are interesting confirmatory evidence, they are not really
essential to the proof of formation by the sea and recent up-
lift, for the topographic evidence is of a thoroughly conclusive
sort.
* The literature of the subject is still very limited. The following are a
few of the more important references :
a. Francisco Vidal Gormaz, Depressions and elevations of the southern
archipelagoes of Chile (Scottish Geograph. Mag., Jan., 1902).
b. Von Otto Nordenskjold, Ueber einige Hrzlagerstatten der Atacama-
wiiste (11 B. Geol. 1. Univ. Upsala, iv, 1898).
c. D. H. Evans, Notes on the Raised Beaches of Taltai (Quart. Jour.
Geol. Soe., xliii, 1907). .
d. Charles Darwin, A Naturalist’s Voyage, etc. Ed. of 1860.
Lf. Bowman— Physiography of the Central Andes. 201
Interior Features.
The evidences along the west coast of South America of
recent tectonic adjustments are particularly ciear because the
uplifts which express these readjustments have occurred on
the seashore, where a standard surface makes reasonably safe
comparisons of relative land levels possible. They are particu-
larly convincing by reason of the freshness of the uplifted
shore forms, a fact owing to the recency of their occurrence at
high levels and to the extreme aridity of the climate in which
these forms oceur, with their consequent freedom from the
obliterating effects of rainwash, aided by chemical decay.
This juxtaposition of recently made shore forms and compe-
tent agent of formation enables physiographic determinations
to be made without hesitation.
It is a matter of great significance, from both the geological
oo)
and the geographical viewpoint, to ascertain how venerally “this
crustal deformation affected the interior portions ‘of the central
Andes. None of the geological arguments so far advanced by
those who have examined the field has included any recogni-
tion of the clear evidences of crustal movements exhibited by
topographic and drainage lines, and allied phenomena. In
every case the arguments have rested upon purely paleontolog-
ical or structural evidence. Furthermore, in the majority of
eases, the analysis of drainage adjustments or directions is
made with sole reference to and in close conformity with the
presumptions raised by the strictly geological conclusions.
Thus, for example, it is often argued that formerly the great
interior sea of central Bolivia dischar ved into what is now the
Amazon basin by way of the La Paz river, whose gorge
through the Eastern Andes forms one of the profoundest clefts
of that region. Now, whatever geological suggestions there
may be for such an assumption, it 1s certain that the DBS 10;
graphic evidence (see Part II, The Eastern Andes) annuls the
supposition in the clearest possible manner. Nor is this the
only disadvantage which the present interpretations suffer.
As “geological histor y, the recor d of fluctuations of land level
are of great importance even when such fluctuations are not
marked by sedimentary deposits. They may condition, for
example, the climate of the region and the character of the
sediments which may ultimately exist; or they may form, as
actually in the central Andes, the lost inembers in time of the
series of recent geological occurrences. Their omission
under the last-named circumstances means the omission of a
part of the geological record in as important a sense as if
glacial events and the forms which express them were omitted
from the record. The fluctuations of level in the interior of
202 I. Bowman—Physiography of the Central Andes.
the region are also easy to read, like those on the coast, but
depend for their recognition upon a wholly different set of
land-form relationships. These, and the considerations to
which they give rise, will form the substance of the succeed-
ing pare agraphs.
Fic. 4.
Tquique Volcanoes Surmounting Eastern Plateau
Coast Ranges the: Western Plateau Santa Rosa
- Salars s | Elke: Oruro Cochabamba Piedmont
7 Biden : Great Central Basin ‘Plains
400 MILES
Lake Huasco
Srililica Pass Satars of Uyun ,
; Llica andCotpasa Lake RBSRg
Iquique
aCe ast Ranges
Pica
SRS RGeis Pica
‘gneous Racks of complex
tructure, Granites, Fe/lsites and bandedFPorphyries partially
Covered with recent Volcanic Products
A WESTERN PLATEAU
Tunart and City of
Western Front
C7) abamba
Oruro: ecco wy : Inca Corral, EasternFrent
: ~ : Pied mont
Slat. tzé s.58e = Serta
ates, Guartzites and ScAé) —= S andstont=se See
Bo SA Sane ann PLATEAU
Fie. 4. Semi-diagrammatic topographic cross-section of typical condi-
tions from Iquique, Chile, tc Santa Rosa, Bolivia.
The dominating features of the central Andes (fig. 4) are
two great plateaus with a central basin between them. The
plateaus trend north and south and are depicted on the physi-
cal maps as two roughly-parallel mountain chains commonly
referred to asthe Eastern and Western Andes. In Bolivia, the
eastern Andes are frequently and variously designated as the
Cordillera Oriental, Eastern Cordillera, Cordillera of the East, or
the Cordillera Real, the latter being an improper extension of the
specific term applied to the lofty snow-capped mountain range
near La Paz that is terminated on the south by El [limani
and on the north by Sorata. The Western Andes are usually
called the Maritime Cordillera,* a generic term applied to the
aggregations of individual peaks and short volcanic ranges
which surmount the western plateau. In addition, specific
terms are applied to the culminating ranges. Thus, on the
aes y between Chile and Bolivia, latitude 20° south, there
the Cerro de Sillilica, just as in southern Peru the mountain
ae at Vilcanote is called the Cerro de Vileanote. Likewise
in the eastern plateau the exceptional heights or the crests of
the declivities that border basins and valleys are given specific
names, as the Tunari de Cochabamba, the Cerro de Cliza, the
Cordillera de Potosi, ete.
*C. R. Markham, Bolivia (Mills’s International Geography, p. 840, 1901).
I. Bowman—Physiography of the Central Andes. 2038
Between the two great Andine tablelands and their super-
imposed peaks and ranges is the central basin or plateau of
lower altitude than the bordermg highlands, separated
from the latter by the two great roughly-parallel scarps of
marked rectilinear quality often for long distances. This is
the alti-plano or “planicie” of Bolivia. It is without outlet
to the sea, an interior drainage basin, and therefore technically*
apart of the true desert area of the world. On the north
the bordering scarps converge in latitude 14° south, enclosing
Lake Titicaca, whose waters discharge by way of the Desa-
guadero river into Lake Poopo, only to be discharged in turn -
into the Salar de Coipasa and the adjacent salars to the south.
Here and there the otherwise flat basin floor is broken by
piles of voleanic detritus, lava flows from occasional centers of
igneous activity, as the Isla de Panza, of Poopo; or by ancient
and highly crumpled sedimentaries, as where the upturned
edges of slates and quartzites rib the hills back of the port
of Desaguadero. East of the central Andes, as indeed along
the whole eastern front of the Andine Cordillera, from the
Argentine pampas to the llanos of Venezuela, the dissection of
the adjacent highlands has been accompanied by the formation
of extensive piedmont deposits. The western plateau descends
by a relatively smooth slope to the coastal deserts of Tara-
paca and Atacama. Between these deserts and the Pacific
shore are low mountain ranges of complex geologic and physio-
graphic character, the coast ranges of Chili and Peru.
With this general statement ne the lie of the land and its
principal topographic outlines, we shall next consider current
explanations and then the more technical aspects of the plhysi-
ography, the genesis and development through time, of the
principal topographic and drainage features.
All of the older and most of the newer descriptive text-books
of geography describe the western Andes as a majestic line of
lofty volcanoes with deep abysses and precipitous walls and
canyons, a stupendous volcanic pile rising sheer from the sea.
This conception was natural to the text-book writer reading
the traveler’s account of lofty Chimborazo, whose white summit
(21,000 ft.) is visible on clear days from the culf of Guayaquil ;
or of El Misti, with 11,000 ft. of relative altitude, at Arequipa,
Peru. True it is that in the south, where the Patagonian
Andes terminate this great orographic system, there is a
mountain-bordered shore which for scenic orandeur meets the
expectations of the liveliest imagination. But the peaks are here
not volcanic cones and the absolute altitudes fall far short of those
* Dr. John Murray, Origin and Character of the Sahara, Science, vol. xvi,
p. 106, 1890.
204. L. Bowman—Physiography of the Central Andes.
in other parts of the system. It 1s a common experience to
find these conceptions ‘of the early books generally held to-day.
Two specific examples trom reasonably authoritative sources
will be accepted as the standard conceptions current among
students of the subject. These will form points of departure
for the new considerations which follow. The first deals with
both the eastern and western “mountain” (plateau) systems,
the second with the western only. The one is a compilation
by Herber tson from various original sources, and is taken from
Mills’s International Geogr: aphy, a a superior and strictly mod-
ern eae work; the other from Sievers, the best general
German work on South America. Herbertson describes the
Central Andes as follows:
“From 40° §. to 4° 8. the Western and Eastern regions of
the Cordillera differ both in composition and age. The East-
ern ranges were folded earlier than the Western ranges,
where the folds are more marked. A series of young volcanic
rocks comes between the Eastern and Western regions; and
along a line which ciings to the Eastern foot of the Western
or main range, there are numerous active volcanoes. The
Western range remains uniform in structure thoughout its
vast length” (p. 817).
The second reference is to Sievers’ Siid und Mittel-A merika,
published in 1908. ‘“ Diese Vuleane sind der Westcordillera
aufgesetzt, erheben sich tiber das 4000 bis 4500 m hohe Grund-
gebir ge zu hohen von mehr als 6000 m und geben dem Gebirge
seine characteristische Erscheinung” (p. 890). It cannot be
denied that from the purely scenic standpoint the volcanoes
are the principal features of the western Cordillera, but from
the morphologic standpoint they are of far lesser importance
than the platform (the “Grundgebirge” of Sievers) upon
which they rest.
The best corrective to the notion that the central portion of
the Maritime Andes owe their height chiefly or even largely
to voleanic accumulation, or that they consist in the main of
a series of meridional ranges, is to be found in the appearance
they present from any point on the Lagunas nitrate railway
back of Tquique, Chile, from Pintados southward. It is hard
to conceal one’s astonishment on first catching sight of the
ereat highland which there lies on the eastern horizon, pre-
senting as it does for at least forty miles in a north-south
direction an unbroken summit so nearly absolutely level as to
give an appearance of pronounced artificiality. It is this fact,
supported by a score of similar ones from widely separated
points, that supphes the organizing panei in the physi-
ography of this whole region. It will be shown that we have
here an uplitted peneplain, whose position 14,000 ft. above
I. Bowman—Physiography of the Central Andes. 205
sea level, constitutes it one of the most interesting and import-
ant physiographic units to be found anywhere upon the earth,
particularly as large portions of it, by virtue of the pr onounced
aridity of the climate even at these high elevations, have
remained in a relatively undissected and therefore safely deter-
minable condition up to the present time.
Every step of the traveler’s approach to this great uplift
increases his astonishment at the perfection of the but slightly
modified peneplain remnant there disclosed. The view repre-
sented in fig. 5 gives one but an inadequate notion of the
perfection it displays.
Fie 95
4 > eee ee se en ee
ae = —— Berea ae ge eee
Fic. 5. The ‘‘crest” and western slope of the Maritime Andes ( plateau)
as seen from east of Pica, Chile.
On the left orth) are the unexplored Altos de Sitilea, pre-
sumably voleanic, and on the right (40 miles farther south) are
the gentle outlines of the Chacarilla mountains. Between
these two volcanic piles is the unbroken levei of the plateau.
The winding precipitous gorges (quebradas) nick its edge
deeply, but at a distance even this mark of dissection is
unobservable and only the impressively level sky-line stands
out sharp and distinct. A straight-edge projected under the
line does not enable the eye to discover a single important
departure from horizontality in the whole forty-mile section.
The same regularity marks the descent of the western edge
of the platean beneath piedmont deposits. The average of
many observations gives T° as the mean value of this descent
while the mean descent of the overlapping piedmont surface
lies somewhere between 3° and 5°. This relation is expressed
in fig. 6.
One of the best localities for the study of the peneplain sur-
face whose warped slope descends beneath the piedmont is
found a long half-day’s journey east of Pica, or about 70 miles
east of Iquique and a short distance north of the trail to Lake
Huasco. The altitude is 5,800 ft.* (A. T.) There, in the
bottom of the Quisma gorge is a pronounced unconformity
showing sandstones, conglomerates, and more recent alluvium,
* Aneroid determinations are to be understood in every case unless it is
specifically indicated otherwise.
206 L. Bowman—Physiography of the Central Andes.
of variable degrees of induration, lying upon light-colored fel-
site. The unconformity is singularly regular and shows on
the one hand a smooth surtace gradually descending beneath
the piedmont, while on the other it ascends with ejually regu-
lar slope to the summit of the plateau fifteen to twenty
miles to the east. The line of unconformity as it appears at
Fie. 6.
Fie. 6. Erosion surface between piedmont and underlying igneous rocks
east of Pica, Chile. The surface may be distinguished by differences of
shade in right background.
10,100 ft. is represented in fig. 6, where the upper lighter pied-
mont deposit is shown resting upon the felsite. The ascent of
the slope leading to the summit of the plateau discloses a sur-
face thinly veneered with slabs and flat stones of great dimen-
sional heterogeneity. This fragmental material is clearly the
result of the extremes of night and day temperatures, for, in
the practical absence of vegetation and at these altitudes 8,500
to 15,000 ft. above the sea, solar radiation, especially during
summer, heats the rock to an incredibly high temperature,
while at night the rare atmosphere favors equally pro-
nounced terrestrial radiation under an unclouded sky. The
consequence is a continual rock peeling, a process only obscured
when the action has continued to the point when a protective
I. Bowman—Physiography of the Central Andes. 207
~
cover has been formed in Fie.
spite of the continual re-
moval of the smaller prod-
ucts by winds and a small |
amount of rainwash. Fine
material, in general present
in great quantities when
rock is chemically decayed,
is here practically absent
and but partially fills the
interstices among the slabs
and blocks. It is acluttered
slope, minutely rough, but
in its distant aspect it is of
gentle declivity and great
smoothness.
Somewhat regularly
spaced along the western
descent are the steep-walled
gorges of the westward flow-
ing streams. Their descent
is gentler than the 7° slope
of the platean margin; and
In many cases they have cut
profound canyons toward
their headwaters. The Que-
brada Quisma of fig. 6 is
several hundred feet deep
where the trail ascends its
walls at 13,000 to 14,000 ft.
elevation, east of Pica. The
Chacarilla gorge, farther
south, is nearly a half mile
deep between the Victoria
mines and the oasis of Chaia.
The stream profiles, in spite
of the adjustments repre-
sented by these enormous
clefts, are still abnormal and
show a steepening of the
lower sections over the upper
below the point where they
pass the edge of the plateau,
thus clearly reflecting the
effects of recent elevation.
From 12,500 ft. to 13,000
ft. the edge of the plateau i 18 :
occasionally marked by rock |
ledges 20 to 40 ft. high.
Fault scarp in left background. Twenty-five
Undissected peneplain remnant on the western border of Lake Huasco.
4.
miles of country in view.
Fie.
208 L. Bowman—Physiography of the Central Andes.
Their crumbling scarps are the last ascent one makes in reaching
the upper level of the plateau. From this altitude to the highest
altitude one attains on the peneplain remnants of this vicinity
(15,000 ft.) the slopes are relatively gentler. Nowhere does
one gain a more impressive notion. of the extent and charac-
ter of these undissected surfaces as from the 12,500 ft. level
east of the spring at Laguno Huasco, fig. 8. The photograph
(tig. 7) searcely needs an interpr etive text. In it one looks a
little north of west and observes from foreground to back-
ground about 25 miles of country, and perhaps an equal dis-
tance from left to right. The plateau surface frequently
referred to above is on the sky-line. The camera stands upon
a great alluvial fan tributary to the basin of Lake Huaseo; and
the basin itself 1s limited on the west by the bold and ragoed
thousand-foot scarp that descends toward the observer im the
middle distance. The degree of baseleveline attained in this
region is brought out strikingly in this view as well as in fig. 6,
where, however, it occupies a warped attitude, assumed since
peneplanation.
It would be singular indeed if the great altitude of the old
surface tlus described had been acquired in a single period of
crustal deformation. The history of other regions raises the
expectation that successive uplifts, rather than a single pro-
found uplift, would occur, separated by periods of “relative
quiet during which the drainage lines and the topography
would become organized with respect to the new base level.
This expectation is more definitely and abundantly met in the
eastern plateau than in the western, by reason of climatic influ-
ences to be defined later, but even in the western plateau we
have specific cases pointing to this conclusion.
The fact of successive uplifts may perhaps be presented more
clearly after some consideration of the present attitude of the
deformed peneplain where block faulting has occurred. In
fig. 6 the gently warped, western slope of the plateau is repre-
sented as a practically smooth descent with but minor disloca-
tions. These dislocations have a considerable interpretive
value, as will appear in the further discussion, but they do not
destroy the general regularity of the flanking slope. In fig. 7
it has already been noted that while a portion of the peneplain
occupies a nearly flat position, its continuity is broken m the
middle distance e a thousand-foot slope and scarp, the west-
ern border of the basin of Lake Hnuasco.
The basin quadrant which lies to the southeast of Lake
Huasco, fig. 8, is a huge fault block which gained its present
attitude after peneplanation. The searp which limits the basin
on the west is the locus of the fault, and the basin itself is the
product of a dislocation whereby the western edge of the block
I. Bowman—Physiography of the Central Andes. 209
retained its initial altitude after uplift while the eastern por-
tion was depressed; the basin thus formed receives a limited
rainfall, and even in the wetter climate once prevailing had no
outlet to the sea.
The fact that this blocked quadrant was formerly baseleveled
appears from the relation between surface and structure that
obtains in the gorge of Rinconado, which enters the basin
immediately south of the twin peaks of Huasco. The gorge is
200 ft. in depth, with nearly vertical sides, and reveals a
clearly featured section. The granite-gneiss forming the body
* co) e e e e
of the block has many structural deformities, a fact which is
IPGie thee
‘
Twin Peaks) \ /
ME oF 1} tes
ST
t Sue oP /
7 y
\qZzSom./ ook
‘ P2g3
Sos
i 4
| Uf
THE LAKE HUASCO REGION
CHILE AND BOLIVIA
oF
: sh —— A
by Isaiah Bowman Huasto Liper ecto
Based on Milikary Maps o prac: \
the Oficina deli mites, Chile, NZ / \ !
and on Surveys of the Yale
South American Expedition of
1907
~-— Drainage © eB eB Corals ¢ Seri
Trai ist Scaresiine: oot
6b 60 2 668° 50
variously expressed, in some places by faults impossible of
restoration on account of the homogeneity of the mass; in
other places by anticlinal structures. The present surface of
the block is exceedingly regular and smooth except where
locally roughened by stream dissection ; and is remarkable for
the exact regularity with which it cuts across the irregularities
of structure. This truncated condition coupled with the
extraordinary evenness of the blocks in their general aspect
forms one of the most constant and striking features of the
region. The block now slopes northwest, occupying a tilted
position with respect to its plane of origin.
The fault scarp of the western edge of the basin, the locus
of movement for the tabled block constituting the southeastern
quadrant of the basin, has been but shghtly modified by stream
erosion since faulting. It possesses two important genetic
qualities which reveal its true nature. First of all, the material
composing the block thus scarped is essentially identical in
* Refer to parallels for correction of scale.
210 L. Bowman—Physiography of the Central Andes.
hithologic character with the downfaulted block forming the
southeastern quadrant just described. It possesses no textural
peculiarities which might account for the formation of the
great thousand-foot declivity of remarkable simplicity, straight-
ness, and definiteness of trend. If further evidence were
needed that the succession of events were the formation of
structural irregularities, peneplanation, and block faulting, it is
to be found on the face of the scarp here considered, where
the flat upper surfaces of the block, a peneplain remnant of
unmistakable identity, is suddenly terminated by this great
rectilinear wall. Furthermore, not only the succession of the
major events which those conditions signify, but also the fact
of faulting is established by the manner in which this recti-
linear scarp trends regardless of structure. While time did
not permit the detailed examination of the structural geology,
it was forcibly impressed by the evidence of several critical
localities that we have here that inharmonious relation of
mountain form and mountain front to structural axes so signifi-
cant of long intervals of topographic development between
periods of crustal deformation.
It is the lack of correspondence between the trend of the
scarp and that of the structural axes that at once dismisses the
initial structure as the cause of the scarp and establishes the
fact that the scarp was formed in a second structural epoch.
That this second epoch is of much more recent date and quite
unassociated with the first in time, as the above consideration
shows it to be different in kind, is established by the length of
time required for the old flat surface to attain the perfection
here displayed and the well-nigh complete discordance it
exhibits with respect to the initial structure. The peneplain
thus bevels the first set of structures and is itself cut into large
well-defined remnants, or blocks, by the second and much
later set of structures—the fault planes which are the loci of
recent block displacements.
At the time of major displacement the Huasco basin must
have been lowest in its northwestern extension, this being the
direction in which the southeastern block quadrant was tilted.
At present the salt lake of Huasco occupies a position south of
the center of the basin, having been displaced from its earlier
more northerly position by the filling of waste material in the
form of enormous alluvial fans heading in the valleys among
the lofty voleanoes which occur in this direction. These great
volcanoes (fig. 8) are a portion of the Sillilica range, the most
important members being V. Sillilica, the twin peaks of
Huasco, Sacaba, and Mt. Divisadero.
The volcanoes rest upon the broken and tilted fragments of
the peneplain which is clearly discernible about the borders of
I. Bowman— Physiography of the Central Andes. 211
their flows but which becomes indistinguishable beneath the
mass of voleanic detritus in the heart of the range. An impor-
tant feature of the outlying volcanoes such as the volcano
Pelaya, on the southern border of the Borateras de Isma, is
the apparently complete adjustment of their lava flows to the
present attitude of the tilted blocks which they surmount. It
is especially noteworthy here by virtue of the strong tilt
imposed upon the block that is the impediment; and indicates,
for this case at least, the fact that some of the voleanic flows
were later episodes than the block faulting. The voleano in
point is on the western side of the borax plain called the Salar
de Empesa (see general map of Bolivia). One of the flows
from its erater forms the steep wall on the south side of the
bay, the Boratero de Isma, that juts toward the west from the
main depression. The principal basin itself is but the down-
faulted block whose nature is sufficiently well indicated by the
800-foot fault scarp that forms its southeastern margin and
visible from the west side of the lake as a steep and nearly
straight wall, cutting across a thick series of earlier and now
deformed mass of igneous rocks.
These descriptions of the present condition of the once
lower and flatter peneplain, and the proof of its existence,
enables the brief presentation of a few facts which seem to
indicate two periods of uplift separated by alternate intervals
of quiet. The first is the occurrence of terraces just within
the edge of the plateau. These are well-defined and are
clearly not of structural origin, the rock in this locality, Que-
brada Quisma, being massive crystalline. The descent of the
upper valley slope from the topmost level of the plateau is rela-
tively gentle and the top of the terrace descends with still
gentler grade to the exceedingly steep descent of the gorge-
like inner valley. The terrace is conspicuous virtually to the
head of the valley—ten miles eastward—and continues down
stream to within a half mile of the edge of the plateau. Here
it disappears, the flat upper slope being displaced by a continu-
ous and steep descent to the valley bottom. Such a terrace
originates the conception of two uplifts. The first was fol-
lowed by valley development to the point of well-graded val-
ley slopes, although the dissection of the flat plateau surface
had only been begun on account of the aridity which charac-
terizes the region. The second uplift is marked by that deep
dissection which the now incised stream has accomplished.
The inner valley is a narrow gorge with persistently steep and
in places vertical sides, a contrasting condition with respect to
the outer valley, which suggests that the time that has elapsed
since the last uplift is short compared with the interval between
the two uplifts.
eg tea Bowman—Physiograph y of the Central Andes.
Confirmatory evidence of general uplift with respect to
which the present drainage has not yet been adjusted is found
in the abnormal profile of the thalweg of Quebrada Quisma an
eighth of a mile eastward of the edge of the plateau. From a
relatively flat upper portion a change is made to a steeper
gradient virtually on the edge of the plateau. * This condition
was accurately determined by field measurements.
A second feature interpreted as a probable indication of two
periods of displacement of the blocked sections of the pene-
plain, is worthy of note here. It suggests that these displace-
ments were accompaniments of the general uplift that the
region experienced and therefore but the different expression
of a cause common to the two adjustments. It is the appear-
ance of the edge of the block illustrated by fig. 7. The upper
part of the scarp descends by a somewhat smooth and rela-
tively gentle slope to a shoulder of more or less definition
where the descent is continued with distinctly increased steep-
ness to the foot of the scarp. The effect on the drainage lines
is to give them all reverse curve profiles but slightly read-
justed to the present outline of the edge of the block. This
appearance is very striking as one views the block of fig. 7
from the lower slopes of the twin peaks of Huasco. It also
comes out with great distinctness as one descends the trail
from the southwest to the spring at the western edge of the
basin and passes In review the various features indicated.
It is concluded that this relation of ape and lower slopes
signifies two periods of faulting separated by a pronounced
interval of stability in the relative positions of the affected
blocks. The upper slopes would, if this view be correct, repre-
sent the graded condition which was reached after the first
period of Faulting, while the renewal of the fault would again
detine the face of the block by recreating the fault scarp.
In a desert region of active faulting the opportunities for
the occurrence of antecedent drainage are obviously dimin-
ished as compared with the possibilities of a humid region. It
therefore did not seem probable when the field was first
examined that any clear cases would be discovered where
the present attitude of the block would be disregarded by a
transverse stream. Indeed, all of the first streams examined
about the Lake Huasco district showed strong conformity with
the dominating slopes. It was, therefore, very gratifying to
find, in the last inspection of the field on the return journey
* An interesting topographic complexity is exhibited in the last three-
quarters of a mile within the margin of the plateau. It consists of a second
terrace distinctly below the level of the first and of decidedly limited devel-
opment. The origin of this second terrace is, however, not of immediate
interest here and will be described in a later paper.
I. Bowman—Physiography of the Central Andes. 218
across the Maritime Andes, a clear case of such antecedency.
The oceurrence is just south of the volcano Hoailla, a full
half day’s ride southeast of Lake Huasco. From a low, flat
divide, a fourth of a mile or more across, a valley begins whose
descent is west toward Lake Huasco, to which it is tributary.
The valley is at first flat-bottomed with tiny meander scallops
on the margin of the valley flat. It continues with this char-
acter a half mile or more, then deepens and narrows gradually,
and is finally transformed into a gorge a half mile long that
transects the edge of the block.
This feature has significance in the analysis of the landscape
hereabout, in that it clearly establishes the fact of deforma-
tion after the establishment of definite drainage lines upon a
flatter surface. The persistence of the downcutting stream,
across the uplift, has resulted in the curious aspect of a stream
flowing westward in a direction precisely opposite to that sug-
gested by the general eastward slope of the block to-day.
The conditions described in the preceding paragraphs occur
chiefly in the Lake Huasco region. We shall now turn toa
more southerly district, that of the Chacarilla mountains, for
topographic and structural features of the greatest importance
in the interpretation of the western Andes.
Fic. 9.
—
ZW TS -——
SN SS
= Ne Rare erage Suen Soa buNe EE aE aE eae ory e TEE EE
~N\ = soe tet aes 2 ie
Hi CRN ACen ae
a OO er
= ie
tj:2-ixé(S==
Ze =
Fic. 9.—Fifteen-mile semi-diagrammatic section of the Chacarilla gorge
on the western slope of the Maritime Andes, east of Allianza, Chile.
Were clear evidence lacking in other localities of a pro-
tracted period of erosion during which the land surface, now a
part of the western Andes, was reduced to a plain of slight
relief, it would suffice to rest the proof upon the evidence
afforded in the walls of the Chacarilla gorge. Here is dis-
played for fully fifteen miles, namely, from above the oasis of
Chacarila to Algarrobal, an unconformity of exceptional defini-
tion. Fig. 9, which displays it diagrammatically, scarcely
needs interpretation. Below the unconformity is a banded
rock of diverse structure, only suggested by the details of the
figure. These structural irregularities are planed off with
great regularity, and are overlaid by a thick series of flat sand-
stones and conglomerates. The unconformity is easily located
in the field, not only by the structural contrasts suggested in
the sketch but as well by the contrasted topographic architec-
Am. Jour. Sci.—Fourts Srrizs, Vout. XXVIII, No. 165.—Srepremper, 1909.
15
214 1. Bowman—Physiography of the Central Andes.
ture in the gorge wall above and below the contact. The
sandstones and conglomerates weather with typical Grand Can-
yon effects,—an alter nating series of vertical scarps and sloping
taluses characterizing the upper part of the section, while the
lower part is irregularly dissected, presenting every complex-
ity of slope arrangeinent. Above Chacarilla the piedmont
deposit thins out and disappears towards the edge of the
plateau.
The distance from the ecrestline of the Andes (east of the
Chacarilla mountains) to the seacoast is approximately 80
miles. At Cerro Gordo a distinct block rises above the pied-
mont slope, breaking its continuity for several miles, and again
directly west of the Pique pumping station, a eranite block
juts sharply above (500 ft.) the general level. In the well-nigh
absolutely arid climate of the region the but partially rounded
edges of these blocks reflect their original outlines with remark-
able distinctness. The upper surface of the Pique block (8,500
ft.) is flat to gently rolling, only rounded knobs of slight ~
extent surmounting the generally even surface. The pene-
plained character of the block appears from the general even-
ness of its surface as developed on rocks of diverse structure
and hardness. The western part of the block is composed
of sandstones, the eastern of a fine-grained resistant igneous
rock, both reduced to a common level. Toward the eastern
margin the surface becomes slightly dissected, long tans of
waste choking the mouths of ravines and stretching out over
the saline crust that forms the salars, the stark desert places
of the province of Tarapaca. Such dissection is, however,
decidedly inconsequent on the whole; the ineffective drainage
results, even on the ravine sides, in a waste cover so deep that
only here and there are rock outcrops distinguishable. The
edge of the block is, therefore, clearly limned as a strikingly
even and abrupt escarpment, but imperfectly dissected by the
feeble, intermittent streams.
The view from the Allanza nitrate station of that part of the
now warped and uplifted peneplain which includes the Chaca-
rilla mountains is represented in the rough sketch in fig. 10.
The summit of the upwarped plateau retains the general charac-
ter here depicted, southward beyond Santa Fé in the Loa
Valley (see general map of Chile). At Calama the old
initial surface was again observed as a tilted block south of the
oasis of that name, where it stands out with unfailing clearness.
This baseleveled ‘surface, with whose identification, broad
aspects, and detailed character at critical localities we have
thus far been concerned, has thus been observed to occur for
over one hundred miles, from Calama to Tarapaca. It will be
I. Bowman—Physiography of the Central Andes. 215
of interest to note how generally it occurs in other parts of the
central Andes.
While opportunity was not afforded to study in the same
detail the interesting plateau section east of Arica, Chile,
the photographs of the plateau, fig. 11, made from the summit
Fic. 10.
Chacaritla Mlns.
Chacarilla
gorge
SSS SSS —-———
Fic. 10.—Detailed view of southern end of sketch, fig. 5, looking east
from Allianza, Chile.
of the 1000 ft. hill northeast of the port of Arica, will suggest
with what probability the peneplain is known to occur in this
locality. The views include about 50 miles of country. The
14,000 ft. (2) tableland constituting the summit of the Cordillera
(bey ond the left of the photogr aphs) i is so flat that this quality,
and not the lofty snow-capped peaks surmounting the tableland,
forms, physiographically considered, the most conspicuous fea.
ture of the landscape. With what structural quality the descent
is made to the intermediate level in the photographs, and what
the genetic relation of these two tablelands is, was not deter-
mined. From the detailed geomorphic study made directly
south, of similar relations, it is not an unreasonable assump-
tion that the two surfaces were once continuous and that the
zone of displacement is represented by the descent from the
upper platform.
The lower wind-swept platform of this vicinity presents a
hard-featured landscape of remarkable flatness, now deeply
covered with drifting sand, now roughly Cloaked with angular
fragments, from eek the Ane material has been sifted by t the
constant wind. It is wonderfully impressive to one who comes
prepared to see a line of precipitous volcanic heights to find
these great flat-topped tablelands dominating the view, only
partially relieved toward evening by the fine appearance of
the distant snow-capped peaks.
Again at Crucero Alto (14, 000 ft.), Peru, on the railway from
Puno to Mollendo, one rises well towards the level of the great
plateau and sees extending out in every direction the topog-
raphy suggested by fig. 12. For phy siographie purposes it
would be useless to deseribe the structure in any detail, so
universally complicated is it. But in spite of the enor mous
plications and irregularities everywhere observable the upper
hy of the Central Andes.
ysiograp
I. Bowman— Ph
216
‘OILY “Volay JO 4svo VoOVJAINS polesojeseq
‘TE “91
LI. Bowman—Physiography of the Central Andes. 217
surface of the plateau remains strikingly true to this level.
West of these localities and toward the coast the initial features
are complicated and rendered indistinguishable by great warps
and faults and by the masses of volcanic debris. that appear
east of Arequipa.
Bree:
Fic. 12. General view of the baseleveled and now uplifted and dissected
Maritime Andes, near Crucero Alto, Peru. Altitude about 14,300 feet.
A study of the map will show the great extent of territory
involved in the explanation here suggested and will clear the
way for the study of the eastern plateau, whose physiography
will be found to have a similar interpretation. In the follow-
ing chapter will also be discussed certain features of the
physiography and geology of the Maritime Andes, which are
best treated in connection with similar features in the eastern
Andes with which they are genetically related.
(End of Part 1.)
Geological Department, Yale University.
218 Pogue, Jr.
Geology and Structure of Volcanic Rocks.
Arr. XXIV.—Geology and Structure of the Ancient Vol-
canie Locks of Davidson County, North Carolina;* by
J: be Pocum,: i
Introductory.
Preliminary statement.—The present article outlines the
more important, non-economic portions of a geological report,
presented as a thesis at Yale University in June, 1909, and
prepared under the direction of the North Carolina. Geological
and Economic Survey. It is based upon three months’ field
work done in the summer of 1908, and upon laboratory and
office work carried on during the autumn, winter, and spring
of 1908-09 in the Petrological Laboratory of the Shettield
Scientific School of Yale University.
Location and geography.—The area described is known as
the Cid Mining District and is situated in the central portion
of North Carolina, within the Piedmont Plateau, and near the
western boundary of a great series of voleano- sedimentary
rocks, the Carolina slate belt, which crosses the state in a
northeast and southwest direction. The tract covers approxi-
mately 125 square miles, and was mapped in detail on the
scale 1: 24,000. The average elevation above sea level is about
600 feet, and the range of elevations within the district is
about 300 feet. This range may be encompassed by long,
almost imperceptible slopes, not disturbing the appearance of
subdued rehef; or by sudden rises, with rugged topography
as aresult. The district accordingly presents not only features
common to gently rolling, maturely dissected regions, but
also in places has a surface configuration comparable to moun-
tainous topography on a small scale. The drainage is into the
Yadkin River, which forms the southwestern boundary of the
area and flows across the str ucture, cutting alike through hard
and soft formations. T’he minor streams, parallel to one
another and at right angles to the Yadkin, are in conformity
with the structure and have thrown into relief northeast trend-
ing ridges, locally called “mountains.” The most conspicuous
of these is Flat Swamp Mountain, which forms a part of Flat
Swamp Ridge extending as a narrow ridge for nearly 7 miles
through the central portion of the district. The region is
sparsely inhabited and contains only a few small villages. It
has been of some importance asa mining center and contains
the Silver Hill, Conrad Hill, Silver Valley, Emmons, Peters,
and other mines—of which the Silver Hill is the best known.
Historical sketch.—It was not until 1894 that the presence
of rocks of voleanic origin within the Piedmont Plateau of
* Published by permission of the State Geologist of North Carolina.
PS
.
x.
,
Pogue, Jr.—Geology and Structure of Volcanic [ocks.. 219
North Carolina was recognized. In that year, George H.
Williams,* in a paper on the distribution of ‘ancient volcanic
rocks along the eastern border of North America, announced
their identification in Chatham County and near Chapel Hill,
and suggested their probable wider distribution. Since then,
Becker,+ Nitze and Hanna,{.Weed and Watson,§ and Graton|
have described in a general way; and Laney, and after him
the writer, have considered in detail areas of these rocks and
established their wide occurrence.
General Geology.
Outline.—The portion of the Piedmont Plateau herein
described exposes the beveled folds of a great volcano-sedi-
mentary formation. <A traverse across the district from north-
west to southeast passes over the eroded edges of once
horizontal beds, which show upon the surface as elongated
belts and lenses. Their character indicates an origin during
a period of great volcanic activity. 7
Wide bands of a sedimentary, slate-like rock, composed of
varying admixtures of volcanic ash and land waste, have the
greatest areal extent. Intercalated with these occur str ips and
lenses of acid and basie volcanic rocks, represented by fine and
coarse-grained voleanic ejectamenta and old lava flows. The.
acid rocks include fine tufis, coarse tuffs, and breccias, chiefly
of a rhyolitie and dacitic character, together with flows of
rhyolite and dacite. The basic series embrace fine tuffs, coarse
tuffs, and breccias of an andesitic nature, and flows of an
andesitic and trachy-andesitic stamp. Gabbro and diabase
dikes cut the other formations.
The region has suffered a period of severe dynamic meta-
mor phism, consequent upon a great. compressive force which
squeezed the beds into enormous folds; followed by a time of
chemical alteration and mineralization ; which in turn was
succeeded by a long period of erosion and weathering. The
rocks have suffered to a variable degree from all these factors.
* Williams, George H., Distribution of Ancient Volcanic Rocks along the
Eastern Border of North America. Jour. Geol., v. ii, 1-31, 1894.
+ Becker, G. F., Gold Fields of the Southern Appalachians. (In U. S.
Geol. Survey, 16th Ann. Rept., pt. 3, 1895.)
{ Nitze, H. B. C., and Hanna, G. B., Gold Deposits of North Carolina.
N. C. Geol. Survey, Bull. 3, 1896.
$ Weed, W. H, and Watson, T. L., The Virginia Copper Deposits. Ee.
Geol., v. i, pp. 309-330, 1906.
| Graton, 1. C., Reconnaissance of some Gold and Tin Deposits of the
Southern Appalachians. U.S. Geol. Survey, Bull. 298, 1906.
S| Laney, F. B., The Gold Hill Mining District of North Carolina. A
Thesis, Yale University, 1908.
Laney, F. B., and Pogue, J. E., Jr., An Outcrop Map of the Virgilina Cop-
per District of North Carolina. Scale 1: 24,000. N.C. Geol. Survey, 1908.
iG aoe
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yvoleanic breccia :
4
breccia ;
Pogue, Jr.—Geology and Structure of Volcanic Rocks. 221
In general, each formation has a massive and a mashed or
schistose phase, with every gradation between the two. The
passage of heated solutions affected all formations, as evidenced
by the mineralized zones, the abundance of quartz veins, and
the high degree of silicification in many belts of rock, and
the universal occurrence of infiltrated iron ores. F inally,
erosion has planed off all the upper portion of the folded series ;
but weathering has proceeded in excess of erosion to such an
extent that the region is now deeply decayed, so that only
here and there do the rocks project through a thick mantle
of decomposed rock or soil.
This threefold set of changes undergone, each cumulative in
its effect, has given rise to an almost infinite number of rock
variations; but a consideration of the rocks which have suffered
the least dynamic and chemical change renders it possible to
establish a definite number of distinct, though related, rock
types, to which the more altered derivatives may be referred.
Slate.-—The rock here designated as “slate” is not a normal
product of land erosion, but bears evidence of a peculiar origin
by a liberal admixture of fine- grained volcanic ejectamenta. alt
occurs in broad bands, with a northeast trend, separated from
each other by belts of voleanic rocks. It shows upon the sur-
face as low, elongated, parallel reefs or ledges. These are
never very abundant nor continuous, because the rock easily
weathers to a soil. Associated with the slate are rather
frequent outcrops of the acid and basic tuffs; the slate in
many places grades imperceptibly into the acid fine tuff.
When fresh the slate is a dark green, dark to light blue, or
grayish black to black rock. With increasing proportions of
ash, these colors grade into lighter shades, and finally into
light grays and whites. Upon weathering, ‘the colors brighten
and become quite diverse and sometimes even brilliant.
Shades of purple, blue, green, red, yellow, and gray, in endless
variations, may appear. In texture, the rock is so dense that
little can be discerned with the unaided eye. In many occur-
rences bedding planes are visible, bespeaking the sedimentary
origin of the rock. Much of the slate is massive, but in many
portions of the district it has been mashed to a greater or less
extent, so that it splits easily along certain directions. Some
of the mashed phases also show bedding planes; these only in
part agree with the schistosity. The rather anomalous term
“schistose slate” seems appropriate for some phases of the
rock.
The most interesting and significant feature in regard to the
slate is the relation between its soda and potash content.
Several analyses show that the ratio of Na,O to K,O varies
222 Pogue, Jr.—Geology and Structure of Volcanic Rocks.
trom 1:1 to 6:1. This excess of soda in a sedimentary rock is
very unusual. For comparison, an average was made of the per-
centages of alkalies found in the 33 dlates analyzed in the
Ahem iaboratory of the United States Geological Survey
from 1880 to 1903,* with this result:
Average Na,O=—0°89 per cent.
. KO= B08 2
The ratio of soda to potash is 1:41. Only two of the 33
slates fail to have at least twice as much potash as soda; and
im no instance is the soda in excess. These figures show that
the material of a normal slate, during an ordinary cycle of land
erosion, loses soda much more readi ily than potash; so that the
final result is a preponderance of potash over soda, irrespective
of the original proportions. When the reverse is found to be
the case, special conditions must be sought to explain this
unnatural relation.
In the slates of the Carolina slate belt, the soda is equal to
or in greater amounts than the potash. According to the
quantitative nomenclature, the Carolina slate is sodipotassie to
dosodie; whereas, a nor mal slate is dopotassic. This feature
indicates that the rock has not undergone a normal cycle of
erosion; for such would have brought it in line with the
average slate. On the contrary, it suggests that the original
material of the rock was transported only a short distance,
and, further, that the material was presented to the transport-
ing agent 1n a condition of mechanical disintegration. <A long
transport of finely comminuted material would have resulted
in the deposition of sediments low in soda. A long period of
chemical weathering, previous to transportation, would have
had the same effect. The conclusion, which is strengthened
by the geologic occurrence, microscopic make-up, and orada-
tion into tuft deposits, is that the slates were derived chiefly
from great masses of volcanic ejectamenta, and deposited by
water, with var ying amounts of land waste, at no great dis-
tance from the source of the material.
The acid series of volcanic rocks. Acid fine tuff —The
acid fine tuff occurs interbedded with the slate and the acid
coarse tuff, and is transitional into each. It has no wide-spread
areal extent, but is abundantly distributed in very narrow
lenses, often represented by single outcrops. These are often
intimately associated with outer ops of the acid coarse tuff, and
the two form tuff bands parallel to the belts of slate. At
times there are frequent alternations in the course of a few
yards between fine tuff, coarse tuff, and slate, bespeaking a
rapid change of conditions during deposition.
* Clarke, F. W., Analyses of Rocks. U. S. Geol. Survey, Bull. 228,
pp. 337-346, 1904.
a
Pogue, Jr.—Geology and Structure of Volcanie Rocks. 228
The rock varies considerably in appearance from place to
place, depending upon its degree of silicification and schis-
tosity. Much of the massive “tuff is highly siliceous, varies
in color from cream through gray to black, and breaks with a
conchoidal fracture into chips with keen, translucent edges.
The outerops are badly jointed and emit a metallic sound
when struck with steel. This type resembles flint or chert
and is locally called “gunflint.” Another phase of the rock
is less dense and not so siliceous; it is usually light gray in
color and appears very finely oranular, Still another phase is
dark green and represents an arenaceous phase of the tuff.
Much of the tine tuff has suffered a variable degree of mash-
ing, so that all gradations are found from the massive rocks
into sericite schists.
The microscopic character and transition mto coarse tuff
establishes the volcanic origin of the fine tuff. It is thought
to cen a volcanic ash of rhyolitic to dacitic character,
which has been indurated, silicified, and altered.
Acid coarse tuff.—The acid coarse tuff occurs associated
with the acid fine tuff in northeast trending belts, separated
from each other by bands of slate country. The rock is also
somewhat extensively distributed as narrow intercalations and
lenses within the slate belts.
In common with most of the rocks of the district, the coarse
tuff is found in all gradations from a massive to a highly
schistose condition. Most of the outcrops reveal their frag-
mental nature on fresh fracture, but with increasing ditliculty
in proportion as the rock is more severely mashed. The out-
crops are abundant and prominent; well rounded when mas-
sive, and narrow and elongated when schistose. The weathered
surface is characteristically bumpy, due to the superior resist-
ance of the fragments, and has a yellowish or grayish color.
On fresh break, the rock is seen to be composed of a dense,
dark colored eroundmass, containing broken crystals of feld-
spar and a variable number of small, angular rock fragments.
The latter are usually one-half inch or less in diameter and
represent several different kinds of rocks. Most abundant are
fragments of a dense, light colored, siliceous rock; but pieces —
of slate, sometimes show’ ing bedding planes, and of a dark
color ed, basic rock are not uncommon.
Along the northwestern edge of the district occurs a broad
belt of sericite schists. These are light colored, extremely
fissile rocks, breaking into thin sheets which are smooth and
soapy to the feel and are quite soft. Upon weathering they
take on the most diverse and brilliant colors, especially near
mineralized zones.. Associated with these occur outcrops
which have not been so badly mashed but that they show their
224 Pogue, Jr.— Geology and Structure of Volcanic Rocks.
original nature and may be recognized as fine and coarse-
ovained acid tuffs. Every oradation can be found from such
comparatively massive occurrences Into the sericite schists ;
these are consequently considered to have been derived through
dynamic metamorphism from the acid tufts.
Those outerops of the coarse tuff which have undergone a
moderate amount of compression assume a peculiar and inter-
esting contour upon weathering. The rock stands up in huge
almond-shaped masses, many of which are 20 feet long, 10
FiG.- 2:
Fic. 2.—duge almond-shaped outcrops of the mashed acid coarse tuff.
feet high, and 5 feet thick at the base. These are abundantly dis-
tributed in troops, as it were; and often scores may be seen,
all in alignment, following the trend of a tuffaceous belt.
Similar outcrops have been aptly described as resembling
enormous military or cockade hats.* These probably represent
slightly more massive phases of the surrounding rock, which
stand up by virtue of this characteristic: enormous kernels or
“augen,” which, fortuitously escaping an extreme of mashing,
were subsequently stripped by the forces of weathering of con-
centric coatings of more schistose rock, until the present elon-
gated cores alone remained.
* Emmons, Ebenezer, Geological Report on the Midland Counties of North
Carolina, p. 52.
Pogue, Jr.— Geology and Structure of Voleanic Rocks. 225
The coarse tuff is mostly rhyolitic to dacitic in character.
Some occurrences contain a large number of andesitic frag-
ments ; and in this way a tr ansition is made into the andesitic
tuffs and breccias.
Acid volcanic breccia.—The acid voleanic breccia is practi-
eally confined to one band, about one-half mile in width, which
extends through the central portion of the district. Asso-
ciated with the breccia are found outcrops of the acid tuffs,
flows of rhyolite and andesite, and long narrow strips of ande-
sitic tuffs and breccias. The acid breccia is twofold in char-
acter, and comprises both a breeciated phase of rhyolite, and
a very coarse tuff, with fragments predominant over eround-
mass and larger in size than one-half inch. The rock is s locally
called “mountain rock ” ; its outcrops are large in size and
extremely abundant. Enormous bowlders up to 20 and 30
feet in diameter are frequent, and with larger, half buried
masses make up rocky ridges which are almost impassable.
Where most exposed, the rock becomes white and pitted upon
its surface. Further weathering forms a porous, sponge-like
exterior which is characteristic. Great concentrically weath-
ered plates are at every stage of peeling off; frequently
spherical shells several yards across may be pried off with a
small pick.
When freshly broken, the breccia has a mottled grayish color.
A great number of light colored, angular fragments make up
most of the surface. Groundmass and broken feldspar pheno-
erysts fill in between the fragments. Irregular masses of dark
green material, present in some phases of the rock, are seen
on close inspection to represent andesitic fragments; these are
never very abundant. In places, phenocrysts and fragments
have an alignment suggestive of fluw structure. Most ‘of the
outcrops are massive.
By a gradual decrease in number and size of fr agments, the
breccia passes imperceptibly into the rhyolite: and in almost
any part of the formation isolated outcrops of the rhyolite
may occur surrounded by the breccia. Part of the breccia,
consequently, is considered a phase of rhyolite brecciated
through flowage. Much of the breccia, however, is probably
an ordinary air breccia. It is impossible to separately delimit
the two phases in the field.
Lhyolite.—Rhyolite occurs in narrow, elongated areas,
associated with the acid voleanic breccia, into which it orades.
It is found best developed along the crest of Flat Sw amp
Mountain. The occurrences repr esent the remains of old lava
flows.
The rhyolite forms prominent, rounded outcrops; and is
predominantly massive and somewhat jointed. — Its surface is
226 Pogue, Jr.— Geology and Structure of Volcanic Rocks.
smooth and of a light gray or white color. In places contorted
and wavy lines, indicative of flowage, are visible. The rock
is brittle and breaks with a conchoidal fracture into pieces
with sharp, translucent edges. Upon fresh fracture, it appears
black, dark green, or evayish o green; with feldspar phenocrysts
uniformly, though not abundantly, distributed. Some phases
are exceedingly dense and can be distinguished with difficulty
from the highly silicified fine tuff.
The analysis of the rock, made by the writer, is as follows:
SiO, Al,O3 Fe,03 FeO MgO CaO Na,.O kK.O H.O COF =Total
74-59. 10°To-~ 1°24 > .2:1t trace 100- 5:39 2:70" 0:61 1-3 0o gales
From this, its position in the quantitative system is eal-
culated to be: Class I, persalane; order 4, quardofelic; rang
2, domalkalic; subrang 4, dosodic. The rock, therefore, cor-
responds to lassenose.
The rhyolite has been completely devitrified since its con-
solidation. According to the nomenclature proposed by
Bascom,* it is an aporhyolite.
Dacite.—Dacite composes the hill east from Cid, known as
Kemp Mountain. It forms here an area of oval outline, about
1 mile long and # mile wide. The rock is distinctly massive
and occurs in numerous, grayish-white, rounded masses,
resembling the outerops of rhyolite. In hand specimen, it is
rather touch, grayish green in color, and has a slightly mottled
surface, due toa few feldspar ‘phenoerysts and to specks
and small patches of biotite and chlorite. A close inspection
reveals that many of the feldspar crystals are green im color
from a slight admixture of epidote.
A feature of interest, brought out by the microscope, is the
fact that auartz does not occur as phenocrysts. It is found,
however, in the groundmass as abundant small crystals of fair
rhombic outline. Similar diliexahedral quartz crystals, show-
ing a rhombic cross section, have been described by Kuch} as
occurring in the gr oundmass of a dacite from South America.
The analysis of the rock, made by Dr. A. S. Wheeler of the
University of North Carolina, is as follows :
SiO, Al,O; Fe.0; FeO MgO CaO Na,.O K.,O H.2O CO, Total
12°38 14:56 0:15 2°22 0°91 2°55 3:40" 2°82 70:30 00090322
In the quantitative system the rock is lassenose: Class I
| J )
persalane; order 4, quardofelic; rang 2, domalkalic; subrang
4, dosodic.
* Bascom, F., The Structure, Origin and Nomenclature of the Acid
Voleanic Rocks of South Mountain, Pennsylvania. Jour. Geol., vi,
p. 827, 1893.
+Kich, Richard, Petrographie [from Geologische Studien in der
Republik Colombia], 1892, p. 69.
Pogue, Jr.— Geology and Structure of Volcanic Rocks. 227
The occurrence probably represents the remnant of an old
surface flow, of slightly more basic nature than the flows of
rhyolite. Its rounded contour on the map is due to the fact
that the observer is not looking down upon the upturned edge
of the flow, but more nearly upon its horizontal surface.
Since there is no direct evidence of flow structure, the mass
may represent an old voleanic neck or conduit, or perhaps an
intrusion or sill which never reached the original surtace.
The basic volcanic rocks. Andesitic jine tuff.—The
andesitic fine tuff represents consolidated dust and ashes from
explosive eruptions of more basic nature than those which
gave rise to the acid series of rocks. Fragments are almost
entirely wanting and are never visible to the unaided eye.
Upon addition of these, the rock passes into the andesitic
tuff and breccia, with which it is closely associated. In no
place is its areal distribution of sufficient extent to show upon
the geologic map. Its separate description is warranted from
its analogy to the acid fine tuff. _
The rock is dense and somewhat less siliceous than its acid
analogue. In color it is either greenish or green mottled with
purple. Outcrops are small, rounded, of grayish-green
exterior, and sandpaper-like surface.
Andesitic coarse tuff and breccia.—The andesitic coarse
tuff, composed of groundmass, phenocrysts, and a subordinate
number of fragments; and the andesitic breccia, with pre-
dominant and larger fragments, are described together. Their
intimate association makes it impossible to separately map the
two.
These rocks form long, narrow strips and broader lenses of
important areal extent, alternating with the areas of slate and
the acid series of voleanic rocks. They range all the way
from massive varieties, made up almost wholly of green frag-
ments, to greenstone schists, which in themselves contain little
evidence of their fragmental nature. The outcrops are abund-
ant and prominent; when massive, they are low and well
rounded ; with increasing degree of schistosity, they become
elongated and narrow, and resemble much in shape great
inverted wedges. Only a few extremely schistose occurrences
fail to have a humpy weathered surface, which reveals the
fragmental nature of the rock, even when this feature is not
observed on fresh fracture.
The massive rock is heavy, tough, dark green, and composed
almost entirely of dark green.fragments up to three-quarters of
an inch and larger in diameter. Dark green material, containing
feldspar phenocrysts, fills the spaces between the fragments.
More schistose varieties appear less fragmental ; the fragments
have been converted into areas of greenish secondary minerals.
228 Pogue, Jr.— Geology and Structure of Volcanic Rocks.
Often the mashed rock is somewhat lghter in color than the
massive varieties.
The microscope reveals the fragments to be of at least four
kinds: (1) fragments of an andesitic flow rock, with a pilo-
taxitic eroundmass of a fluidal texture; (2) fragments of ande-
sitic rock without trachytie arrangement of the feldspar laths ;
(3) fragments of an amygdaloidal andesite; and (4) fragments
of an acid rock, probably a tuff.
The wide distribution’ of the type of rock just described,
and its diversity of contained fragments, suggests the great
complexity of the voleanic period during which it was formed.
There were undoubtedly many alternations between outbreaks
of acid and comparatively basic magmas.
Andesite.— Andesite is of limited occurrence within the dis-
trict. It forms several narrow strips and lenses of small areal
extent, which represent the remnants of old flows. The rock
is massive and mostly porphyritic. One occurrence 1s amygda-
loidal and dotted with small rounded and oval areas of green-
ish material, representing the vesicles of a surface lava subse- |
quently filled with infiltrated material. The outerops are not
large, but are fairly abundant, and are usually rounded.
The porphyritic andesite is a medium to fine-grained rock,
varying in color from a grayish green, or epidote green mottled
with blue, to a dark bluish purple. “All yariations contain
small green specks and masses of epidote. Except in the
densest specimens, the rock is easily seen to be porphyritic;_
the phenocrysts are feldspar laths of variable abundance.
The amygdaloidal phase is an epidote-green rock, abundantly
dotted with rounded and elliptical amygdules, varying in
diameter up to 4"™. These are filled with material of a darker
green color, which in most cases is epidote with chlorite, but
sometimes in part calcite. Near the surface the material
filling the cavities has weathered out, giving to the rock a
honeycombed appearance.
The analysis of the rock, made by the writer, is
SiO. A\le(O)s FeO; FeO MgO CaO Na.O K,O H,O0 COz Total
66°28 10°62 6:41 2:11) 1:10 - 3:17) 6:09) 2 1-73. 0:6 ieee
From this, its position in the quantitative system has been
calculated to be: Class IJ, dosalane; order 4, quardofelic;
rang 1, peralkalic ; subrang 4, dosodic. The rock corresponds
to pantellerose.
The rock on the whole is a very alkalic andesite. Certain
phases have a strong trachy-andesiti¢ stamp. .
Dike rocks. Gabbro.—Gabbro occurs widely and abund-
antly distributed in the form of dikes, trending in a northeast-
southwest direction. In size these vary from one-eighth mile
Pogue, Jr.— Geology and Structure of Volcanic Rocks. 229
in width and 3 to 4 miles in length to ones mdicated only by
the presence of a few bowlders. The rock shows upon the
surface as rounded, yellowish bowlders, ranging in size up to
10 feet in diameter, and distributed in lines following the
trend of the dikes.
The directions of the dikes in all cases coincide with the
schistosity of the formations in which they occur. Also, the
gabbro is itself unmashed. The schistosity is therefore con-
sidered to have been developed prior to the introduction of
the dikes and to have been, as an easy line of yielding, a con-
trolling factor in their entrance.
The contacts between dikes and‘adjacent formations are
much obscured by weathering, so that it is impossible to
discern any contact effects.. The deeply weathered nature of
the contacts, however, bespeaks a zone susceptible to altera-
tion and doubtless rendered so by contact action. Jointing is
well developed, and of such a nature as to suggest the opera-
tion of a compressive force after the introduction of the dikes.
The gabbro isa greenish-gray rock, of medium grain and
homogeneous texture, 1n which erystals of green hornblende
and areas of opaque feldspars may be recognized. ‘The micro-
scope reveals that the hornblende is uralite, secondary after
pyroxene, and that the feldspar has been completely changed
into saussurite, which represents an original plagioclase rich
in lime. The rock is tough and heavy, and is very susceptible
to weathering. In point of age, it is the second youngest
rock in the district, since it cuts the other formations and is
itself cut by dikes of diabase.
Diabase.—The diabase forms narrow dikes uniformly,
though not abundantly, distributed throughout the district.
It shows upon the surface as narrow lines of small rounded
bowlders of an iron-rust color, locally called ‘“niggerheads’’.
The dikes vary in size from a few feet in width and a few yar ds
in length to the largest, which is about 100 feet in width and
slightly over a mile in length. The majority conform to the
former dimensions. In trend they usually vary from N. 30° W.
to N. 30° E. The trends of the dikes coincide with important
joint directions.
The diabase is a massive, fine-grained, dark blue rock, very
tough and with a waxy luster on fresh fracture. Upon exam-
ination it is seen to be a closely knit aggregate of dark-colored
minerals, among which striated feldspars may be distinguished
from the ferromagnesian minerals. Although the rock is high
in olivine, this constituent cannot be megascopically distin-
guished from the augite. The mineral composition, or mode,
determined by the Rosiwal method,* gave : 45°6 per cent
* Rosiwal, Verh. Wien. Geol. Reichsanst., vol. xxxii, p. 143 ff., 1898. Cf.
Cross, Iddings, Pirsson, Washington, The Quantitative Classification of
Igneous Rocks, p. 204.
Am. Jour. Sc1.—FourtH SeriEs, Vou. XXVIII, No. 165.—Srpremper, 1909.
16
230 Pogue, Jr.—Geology and Structure of Voleanie Locks.
plagioclase ; 35°3 per cent augite; 17-4 per cent ee and
1-7 per cent magnetite.
The analysis, made by Dr. A. 8. Wheeler, is:
SiO, Al,O; Fe.0; FeO MgO CaO Na,O K.0 H.O CO, Total
47°66 19:24 1°83 8°67 10°79 9°91 1:14 0°26 0°06 0:00=99°56
From this its position in the quantitative system is calculated
to be: Class III, salfemane; order 5, perfelic; rang 5, per-
caleic ; subrang, not needed. The rock corresponds to
hedabekase,
The diabase is the youngest rock in the district and is prob-
ably of Triassic age. As is well known, dikes of fresh
olivine diabase have a widespread occurrence throughout the
Piedmont Platean, and in many places may be BEE into
areas of Triassic sandstone.
Structural features.
Folding.—The region has been squeezed into great fol
during a period of severe compression, the most evident eflect
of which has been the mashing of many of the rocks into
schists. The folds may not be directly observed, but their
presence is inferred from three concurrent lines of evidence.
1. Bedding planes, which indicate a former horizontal
extent, often depart from this direction, and have a variable
dip either to the northwest or to the southeast, and at times
are even vertical. Were these sufficiently well preserved, they
alone would indicate the exact nature of the folding; but they
are much obscured by schistosity and weathering, so ‘that only
here and there can a measurement be obtained. Certain
generalizations, however, may be made. Bedding planes are
predominantly horizontal along certain northeast-southwest
lines in massive formations ; and tend to be vertical or nearly
so in the badly mashed belts.
2. The surface outlines of the formations, best seen on the
geologic map, are indicative of folding. In eeneral, the forma-
tions may be divided into two classes: first, those which
appear upon the surface as long, narrow stripes, which oradually
pinch out at the ends and never end abruptly against other
formations; and second, those which oceur in broad lenses and
oval areas, of little or no elongation, and often ending abruptly
against other formations. Many of the narrow bands are flow
rocks or tuffs and breccias, which must have been deposited in
layers or beds of horizontal extent. Their surface outline
seems to preclude any other possibility than that they are the
upturned edges of such beds, which now intersect the surface
vertically, or nearly so. Broader lenses and oval areas,
although often composed of the same rock as the narrow stripe,
Pogue, yee Geology and Structure of Volcanic Rocks. 231
ean hardly have the same underground relations. If those,
too, represent the edges of beds, and consequently expose their
cross-section, the abrupt endings of such formations and the
great stoutness of many of the lenses are difficult features to
explain. Besides, the predominance of horizontal bedding
near such formations is quite incompatible with such an idea.
A satisfactory explanation lies in the consideration of these areas
as occurring on the crests of great folds. This position allows
of a most irreeular surface slope, with abrupt endings against
other formations, when planation has exposed a particular bed
to view; and is, moreover, in accord with existing bedding
planes.
3. The relation between schistose and massive formations
throws further light on the structure. Schistosity is not
developed alike in all parts of the area; it appears to have
been the result of a selective action, so that some belts are
predominantly massive, whereas others are strongly schistose.
This cannot be explained by a difference in the nature of the
formations; for the same formation may in one place be
massive, and in another, badly mashed.. The position of a
rock mass, therefore, is apparently a much more important
factor in determining its degree of schistosity than its litho-
logic character. It “follows, accordingly, that, although the
region as a unit was subject to compression, some portions
were so situated as to escape any important effects of such a
force. The crests of folds would afford positions favorable for
the transmission of a great compressive force without 1mpor-
tant molecular adjustments; the limbs would involve a greater
slipping between beds and consequently be susceptible to the
greatest degree of mashing. This assumption best fits the
facts observed.
The three lines of evidence coneur, then, in making pretty
conclusive proof that the region is folded. The exact nature
of the folding is a more difficult thing to determine. Yet an
application of the same three principles indicates that the
region very probably represents in general two anticlines and
one syncline, the axes of which extend in a northeast direction
in agreement with the schistosity. Flat Swamp Ridge is con-
sidered the trough of the syncline ; and the two corresponding
anticlines are near the northeast and southwest borders,
respectively, of the district.
Consequent upon the major folding, a series of subordinate
crumplings and crinklings were of necessity formed; but these
have been so obscured by weathering and other changes
as to bafile detection. Their presence is only indicated by
an occasional bedding plane out of accord with other measure-
ments in its vicinity.
232 Pogue, Jr.—Geology and Structure of Volcanic Rocks.
It is probable, also, that the major folds are not absolutely
horizontal, but pitch. slightly, so their crests form wavy lines.
No direct measurements of pitch can be obtained, but infer-
ence as to its nature may be made from the way in which
certain formations end abruptly against others, as if dipping
beneath them. A further evidence is the occasional discord-
ance between trend of bedding and of schistosity, indicative of
a complexly folded region.*
In addition to these major and minor directions of folding,
whose axes lie in a horizontal plane, the whole region has,
perhaps, been slightly bent around a vertical axis. A glimpse
at the geologic map will disciose the tendency of the schistosity
to form an arc-like arrangement ; in general, varymg from a
northeast trend near tbe river to a more northerly direction as
the upper limits of the map are approached.
Mashing.—Ilt has been suggested in the previous section
how schistosity has been induced upon much of the region by
the same compression which occasioned folding, and how this
has been more prominently developed on the limbs of the
folds than on the crests or in the troughs. A further deduc-
tion, however, may be made from the nature of the schistosity ;
that is, the direction along which the compressive force acted.
The average trend of schistosity is N. 50° E. Theoretically,
therefore, the compression acted along a line passing N. 40° W.,
as the effects of compression are at right angles to the force.t+
This figure must not be taken as exact, for other factors would
complicate the result; but it is approximately true.
The average dip of the schistosity is about 70° to 80° to the
northwest, with extremely few cleavage planes dipping to the
southeast. This is significant. It suggests that the folds are
not upright; for in such a case approximately half of the
schistosity should have a dip to the southeast. Thus there is
evidence for believing that the folds are slightly inclined,
their axial planes agreeing in a general way with the average
dip of the schistosity. This view is consistent with the are-like
arrangement of the formations, which in itself implies a slight
overriding of the upper crust and an axial dipping of the folds
towards the center of the are.
The northwest dip of cleavage planes and northwest-facing
concavity of the arcs is the opposite of conditions holding in
the Appalachians. This may be due either to some undeter-
mined local cause, or to an actual reversal of the relations —
between land oo sea obtaining in the Paleozoic; so that in
*Van Hise, C. R., Principles of North American Pre-Cambrian Geology.
16th Ann. Rept. u 'S. Geol. Survey, 1895, p. 629-630.
+See in this connection Haug, Emile, "Traité de Géologie, vol. i, p. 227,
1907.
Pogue, Jr.—Geology and Structure of Volcanic Rocks. 233
the case of the present area, the higher segment or land mass
was to the northwest, whereas in the case of the Appalachians,
as is generally accepted, the higher segment or “ hinterland ”
of Suess was to the southeast. The district under considera-
tion, however, is too limited in size to afford widespread
generalizations on this point, unless corroborated in the future
by other observations in the slate belt.
Jointing.—Joint planes are distributed throughout the dis-
trict in all formations, but are most abundant in areas of
massive rocks. In general, the degree of jointing decreases
with increased schistosity: the two features seem to be com-
plementary. Where bedding is horizontal, jointing is invariably
well developed.
These features indicate that the jointing is largely the result
of the compressive force of folding. Rock masses situated on
the crests or in the troughs of folds escaped to a large degree
the effects of mashing, but in transmitting the force were
themselves broken into blocks bounded by joint planes.
‘The following conclusions are drawn from a graphical plot-
ting of the jomts. The jointing is grouped into four impor-
tant sets, in their order of importance, as follows:
IN AV. to N 7305 W-
NEG or Wi ato NG 85. W..
NE dg HgetopNv35 ek.
NE GOS We ONG Bao,
There is no important difference in the jointing in the slate
and in the other formations. In massive formations there are
no important joint planes parallel to cleavage planes in schistose
formations. There is no evidence for believing any important
jointing on crests of folds to be due to tension: joints from
such a cause would be parallel to the schistosity developed on
the limbs of the fold.*
All jointing in the region is not considered the result of a
single period of compression. There is doubtless jointing,
also, from other subsequent earth movements.
Faulting.—W hile there is at no place conclusive evidence
of faulting on an important scale, a number of probable faults
have been indicated on the eeologic map. These cannot be
verified by field observation; but their presence is suggested
by the abrupt ending of cer tain formations, as if cut off by
dislocations, and in cross-section by the failure of bands to be
repeated on the corresponding parts of folds. The smaller
faults have a general parallelism to one another, and to
Fourmile Branch, which pursues a remarkably straight course
* Van Hise, C. R., Principles of North American Pre-Cambrian Geology
16th Ann. Report, U.S. Geol. Survey, 1895, p. 669.
934 Pogue, Jr.—Geology and Structure of Volcanic Locks.
for six miles and agrees in direction with two large diabase
dikes. They are also roughly parallel to the strike of a pro-
found fault a few miles to the west, which Laney* has shown
to separate the slate series from a large area of igneous rocks.
A large overthrust fault has been indicated as extending
along the eastern border of Flat Swamp Ridge in a northeast
direction and becoming northerly in trend near the upper
borders of the map. Its presence seems necessitated by the way
in which broad belts of rock appearing on the western slope of
Flat Swamp Ridge are not repeated on its eastern declivity, as
would be expected on the two limbs of a syncline. Either,
then, beds one-half mile or so in thickness must thin out along
their dip in the course of a mile or they must be abruptly cut
Ble Sp Milt AE fil as
f SS af Le ay Pay
os
vp. WSN +t+4t4] [reeL
ae t+teett s3,
af SS 4tttt+t SN
JS t+ttt L
Sl AT An-V-Br An-T-Br An Gb eyel
Fic. 3. Cross-section along the line AB of the geologic map.
Explanation of contractions: Sl, slate; AT, acid tuff; An-V-Br, acid vol-
canic breccia; An-T-Br, andesitic tuff and breccia; An, andesite; Gh, gabbro;
Pr.F, probable faults.
off by a fault. A glance at the cross-section will make this
point clear.
The faulting is probably the result of the same compressive
force which induced folding, schistosity, and jointing. It is
unnecessary to bring in a second great earth movement to
explain this structure. Yet it is possible that the coming to
place of great granitic batholiths a few miles to the west may
have exerted sufficient compression to occasion overthrust
faulting.
Interpretations of structure.
Most probable interpretation.—The reasons have already
been presented for believing the region to be made up of a
series of inclined folds, whose axial planes dip steeply to the
northwest. ‘This interpretation is represented on the accom-
panying cross-section.
In a region, such as the one under consideration, in which
the structural features are so obscure and difficult of access, a
diagram can only attempt to express in a generalized manner
the actual conditions.
* Laney, F. B., The Gold Hill Mining District of North Carolina. A
Thesis, Yale University, 1908, p. 112.
Pogue, Jr.—Geology and Structure of Volcanic Rocks. 235
In the cross-section given no minor crumplings are indicated
on the major folds. Such undoubtedly exist, but they are
omitted both for the sake of simplicity and because their
nature is not known. The thickness of those beds whose
cross-section is in no place exposed upon the surface is entirely
hypothetical. If it be attempted to trace out each formation
as it is successively brought to the surface by the folding, it
will be found that the beds do not always match on the
opposite limbs of the folds. This is understood, if it be
accepted that the original horizontal extent of the formations
consisted of a complicated interfingermg of beds and lenses,
and was not a succession of regular beds of the same thickness
thoughout their lengths. In such a case folding would not
necessarily repeat similar beds on corresponding part of folds.
Along Flat Swamp Ridge, however, this explanation seems
inadequate, inasmuch as beds of great thickness must pinch
out with extreme rapidity in order to avoid repetition. To
obyiate this difficulty, an overthrust fault has been introduced
as stated, as a simpler explanation. The arc-like surface trace
of this supposed fault-plane renders it probably an overthrust
consequent upon the northwest compressive force of folding.
The fault-plane may itself be folded, depending upon whether
the slp occurred-at the beginning or near the end of the
period of folding. ‘The latter conception is preferable, because
simpler.
Alternate hypotheses.—Although the interpretation of struc-
ture given appears to best fit the facts, some alternate hypothe-
sis, especially in regard to the subordinate features, may be
mentioned.
As suggested in previous paragraphs, the entire structure
may be explained without the use of faults.
A portion of the rocks may have been brought into the
region by an overthrust fault; and these subsequently inter-
folded with the regional rocks.
The region may possibly represent a series of isoclinal folds,
with parallel limbs.
That the region may not be folded and represents a very
thick deposit, which has been tilted and whose edge is now
cut across by the plane of erosion, seems hardly a possibility.
Discussion of geologic history.
The geologic history of the Cid district may be considered as
having its beginning during a period of volcanic activity of
long duration. During this time there were innumerable
alternations between quiet upwellings of lava, forming surface
flows; explosive activity on an enormous scale, piling up
236 Pogue, Jr.—Geology and Structure of Volcanic Rocks.
to great thickness deposits of tuffs and br eccias ; and periods of
comparative quiescence, accompanied by some weathering and
erosion and the deposition of the slates. Between successive
outbreaks, the magma probably underwent a certain degree of
differentiation; so as to give rise to acid rocks at one time,
and comparatively basic rocks at others.- It seems evident
that there were frequent swings between two not very diverse
extremes, and that at no time did the product depart far from
the average type—a rather acid rock high in soda. Perhaps
each important outbreak poured forth rhyolitic, intermediate,
and andesitic materials.
It would be impossible to picture the details of this voleanie
activity. It is suggested, however, that the outbreaks were
largely eruptions along fissures, breaking up through the series
of already formed horizontal rocks at. “frequent points in the
_ entire volcanic region.
All of the slate and much of the fine tuff give evidence in
bedding planes of deposition by water. The coarse tuffs and
breccias may be air-laid or water-laid, or both. The flows
may have taken place upon the surface of the land or under
water. Possibly the entire series represents an off-shore
deposit, with submarine volcanic activity alone or accompanied
by outbreaks upon the shore. Or the region may represent a
river flood-plain or delta deposit.
It is believed from chemical evidence that the slate material
was transported from no great distance. Hence a probable
view is to consider the volcano-sedimentary series a basin
deposit, the material for which was derived from beneath an-
area of limited extent, and the thickness of which was hmited
only by the depth of the magma reservoir and the amount of
material extruded. Thus by isostatic sinking of the crust
block capped by a layer of sedimentary and voleanie rocks, as
more material was forced up through it and deposited upon
its top, a series of great thickness could have been formed,
without drawing materially upon the surrounding country for
sediments, and conversely without bestowing evidences of its
nature upon regions not within its own confines.
However laid down, the tuffaceous and sedimentary rocks
must have undergone cementation or consolidation before they
were capable of being thrown into folds. This process doubt-
less accompanied the formation of the deposits.
No evidence is afforded for estimating the length of time
which intervened between the formation of the rock series and
its folding. It may be that the compression put an end to the
constructive epoch; or it may equally be that this force was
long deferred.
BF ollowing the folding after an unknown interval, a great
Pogue, Jr—Geology and Structure of Volcanic Rocks. 287
number of gabbro dikes were insinuated into the region.
These represent either the outhers of an independent eabbro
batholith or the differentiated off-shoots from a large mag-
matic reservoir of more acid nature; and are pr obably related
to great intrusive masses of eranitic, dioritic, and other mass-
ive coarse-grained igneous rocks occurring a few miles to the
west.
The coming to place of the igneous masses, which adjoin
and probably undermine the district, inaugurated a period of
activity of circulation; during which the rocks were mineral-
ized, in part by valuable ores, and universally by pyrite and
pyrrhotite ; many formations enriched “en masse’ 2 by-sili¢ac:
and a large number of quartz veins left along lines of major
circulation. The amount of material introduced seems to pre-
clude any but a magmatic source. It is not known to what
proportional extent, if any, the materials were contributed by
the gabbro or by the large granitic masses. From the great
amount of silica introduced, and from the acid character of
the gangues, it is likely that the granite was the dominant
source.
The first event of practically known age is the introduction
of diabase dikes in Triassic time. There is no evidence for
estimating the length of the interval between the period of ore
deposition and the coming to place of the diabase.
And finally, the forces of weathering and erosion, although
operative since the region was first elevated by folding, have
been especially active from the introduction of the diabase to
the present. This period then is dominantly one of planation
and rock decay: to such an extent, indeed, that the region has’
been reduced once to an approximate base-level, and although
rejuvenated by uplift, is again approaching that state.
Summary of geologic history.
Pre-Cambrian (?) 1. Building up of the volcano-sedimentary
series. Alternation of volcanic activity and periods of
quiescence.
2. Consolidation of the series.
3. Operation of a compressive force, throwing the whole
formation into folds, and inducing schistosity , Jointing, and
probably faulting.
Paleozoic (?) 4. Approach of a mass of igneous rock, announced
by the insinuation of gabbro dikes into the region.
5. Passage of solutions, depositing iron ores and silica, and
forming quartz veins and mineralized zones.
Triassic, 6. Introduction of diabase dikes.
Post-Triassic, 7. Period of weathering and erosion.
238 Pogue, Jr.— Geology and Structure of Volcanic Rocks.
Thickness and age of the slate series.
Thickness.—Nothing definite can be said about the thickness
of the volcano-sedimentary series. From the cross-section,
however, it appears probable that the series is from 2 to 4
miles thick. This estimate is given by no means as a final
figure, but with the hope that future work in the same province
may turn it into something more definite, corroborative or
otherwise.
Age.—Again, nothing final can be said about the age of the
slate series. Jt has generally been considered to be Pre-Cam-
brian. Volcanic rocks of a somewhat similar nature in the
South Mountain region of Pennsylvania occur beneath Cam-
brian sandstone.* As there is no evidence to the contrary,
the present series is provisionally correlated with the Pre-
Cambrian.
Acknowledgments.
In conelusion, the writer wishes to acknowledge his great
indebtedness to the advice and previous work of Dr. F. B.
Laney, whose report on the adjoining Gold Hill District, con-
taining many of the results herein set forth, is now in press.
Also the author desires to thank Professor J oseph Barrell for
suggestions in regard to the structure, and Professor L. V.
Pirsson for interest and advice during the entire investigation
and the preparation of this article.
* Williams, G. H., The Volcanic Rocks of South Mountain in Pennsylvania
and Maryland, this Journal, v. xliv, 493-494, 1892.
W. G. Cady—Electric Arc between Metallic Electrodes. 239
Art. XX V.—On the Electric Arc between Metallic Elec-
modes. by, WG. Cany. Third Paper.*
TV. Tse Properties oF GLow-ArcC OScILLATIONS.
Ty the second paper it was shown that when a discharge at
small current takes place under an impressed e.m.f. of several
hundred volts from a metallic cathode, in a gas which is
preferably a mixture of hydrogen and acetone vapor, rapid
electrical oscillations are generated, of a frequency depending
essentially on the electrical constants of the portions of the
circuit in the neighborhood of the discharge tube. The nature
of the pulsations seems to be a series of rapid changes back
and forth between are and glow.
In the following paragraphs the properties of these oscilla-
tions, as far as they have been examined, will be discussed.
$15. Apparatus.— Preliminary observations showed it to
be desirable to employ a discharge tube with electrodes of as
simple a form as possible, in order that the oscillations might
not encounter a needless amount of resistance or of self-induce-
tance close to the discharge itself. To this end, brass rods
AA (fig. 1), 3"™ in diameter, were extended through corks in
the ends of a glass tube about 10x38". The electrodes
usually employed were discs about 1™ in diameter, with
slightly rounded faces. A number of dises of different metals
but of the same size and shape were made, which could be
serewed on to the rods.
A mixture of hydrogen and acetone vapor was led in
through the glass tube C and out again at Y, where it burned
in a minute flame. was a small side-tube, closed with a
cork, for-the insertion of a brush for cleaning the electrodes.
As only atmospheric pressure was used, no special sealing was
necessary, other than a little soft wax.
The bositive electrode was hardly attacked at all by the
passage of the current, but the cathode showed a small cavity
at each point from which the discharge had taken place. It
was necessary to rotate the cathode slightly from time to time,
as well as to adjust the length of discharge (a few tenths of a
millimeter) with great care. Hence one of the brass rods was
sealed into a glass tube /, which was connected by means of
a straight ground-glass joint to a second tube G, the latter
being sealed into the cork. By having the two rods slightly
eccentric in their mounting, and by rotating / or moving it
slightly in or out, very delicate adjustments were possible.
* Continued from this Journal, vol. xxviii, p. 102, 1909. The paragraphs are
numbered consecutively in the second and third papers.
240 W.G. Cady—Electric Arc between Metallic Electrodes.
$16. As long as the circuit on at least one side of the tube
was free from too large self-inductance or resistance for a few
ineters from the discharge, good oscillations could be obtained.
During most of the experiments large copper wires extended
from the tube about one meter apart fora distance of about
15™ with as few bends as possible. At the farther ends of
jive iL
these wires were first, coils of large self-inductance, then the
regulating resistances, ammeter shunt, and electromotive force,
the latter consisting ‘of asmall 650 volt generator, In series
with which were connected at times about 350 volts additional.
The currents used, ranged from 0°0025 to 0:25 amp., the
strongest oscillations being produced at about 0-1 amp.
A voltmeter connected across the discharge indicated, dur-
ing oscillations, about 215 volts when‘the current was 0-1 amp.
This value, however, cannot be depended upon, for the pres-
ence of the voltmeter as a shunt across the are greatly dimin-
ished the intensity of the oscillations (cf. $31). The true
value of the mean discharge potential was obtained from a
knowledge of the current, e.m.f., and external resistance, and
it proved to be about 280 volts under conditions similar to
those described above. This is intermediate between the volt-
age drop usually found for an are and that for a glow.
When the electrodes were touched together and then
separated slightly, the discharge formed a minute spot of light
between their nearest portions. It was of a bluish color, not
very bright, and differed in appearance from either an are or
a glow. The presence of oscillations penetrating through the
circuit as far as the self-inductance coils was shown by the
heating of a bolometric detector in the neighborhood, or by
the brightening of a pilot lamp in the discharge circuit (see
§ 18).
S17. Alternating current as source of energy for oscila-
/ions.—Oonsidering the shortness of the discharge-gap, it was
thought that a moderately high alternating e.m.f. might suffice
W. G. Cady—Electric Arc between Metallic Electrodes. 241
to maintain the discharge.* Accordingly the voltage of the
60-eycle mains was stepped up to about 880 volts and used in
place of the usual direct-current supply. With an effective
eurrent of about 0°06 amp., oscillations of fair intensity were
produced, with which most of the experiments described
below could be performed.
This use of the alternating current to produce high-fre-
quency oscillations suggests that the effect described by Dud-
dell} in his recent paper on “ short spark phenomena” may be
due to puisations of the kind described in the present article.
$18. Properties of the oscillations.—The following simple
experiments illustrate in a striking manner the properties of
these oscillations. Unfortunately all attempts at increasing
the output of energy have been fruitless, for the maximum
potential difference is only that of a glow discharge, and the
discharge degenerates into a steady are if the current is
increased much above 0°2 amp. A _ close-coupled resonance
transformer reacts upon the discharge, reducing the oscilla-
tions. Still, for purposes of demonstration the oscillations
may find a certain field of usefulness, for they exhibit the
chief properties of high-frequency alternating currents with
extremely simple apparatus. The supply e.m.f. may be alter-
nating, but it is better direct, and the latter is here assumed.
(a) Connect in series with the tube a direct-current ammeter
and an incandescent lamp of about 0°5 amp. capacity. When
the electrodes are touching the ammeter reads, say, 0°2 amp.
and the lamp glows dimly. On separating the electrodes the
ammeter indicates a diminished current, but if oscillations are
present the lamp burns brightly, showing that the effective
alternating current is greater than the direct current supplied
by the generator. From the increase in brightness of the lamp
a rough estimate can be made of the efficiency of conversion
of direct into alternating current. A miniature lamp, or one
of several hundred ohms resistance, may be used equally well.
In nearly all of the work an 8-volt 2-candle power lamp was
kept in series with the discharge tube, and it was found to
serve as an excellent indicator of the presence of oscillations.
(6) Connect a few turns of heavy wire in series with the
tube, and in parallel with this coil place a high-resistance
lamp. The latter glows brightly. It was by this means that
the first estimate of the frequency of the oscillations was made,
in terms of the self-inductance of the coil, and of the resist-
ance and volts (estimated from the light) of the lamp.
- (¢) Connect in series with the tube a miniature lamp, then
@ resistance of several hundred ohms, and finally a second
* Cf, Peukert, Elektrot. Zeitschr., xxiii, p. 562, 1908.
+ Duddell, Proc. Phys. Soc. London, xxi, Part III, p. 275, 1909.
242 W. G@. Cady—Electric Are between Metallic Electrodes.
miniature lamp. The first lamp glows brightly, the second
little or not at all, showing that the oscillations have been
absorbed by the high resistance.
(d) Substitute a “coil of self- inductance, but of low resist-
ance, for the high resistance in (¢). The result is the same
as before, owing to reflection and absorption of the waves by
the self-inductance. These experiments explain the fact that
the remote parts of the circuit are entirely devoid of oscilla-
tions. Thus, if there are connected in series with the dis-
charge a small lamp, a few meters of straight wire, a second
lamp, and a large self-inductance, the lamp nearer to the tube
will brighten up under the oscillations, while the other remains
dark, showing that a node of current is located at the self-
inductance, as if at the end of an open oscillator.
I have repeated these experiments, using a hot-wire
ammeter instead of lamps, and have thus explored various
parts of the cireuit for oscillations. An example of such
observations is shown in Table I. Hach set of readings
Tasre I,
10 O Ts =ir To
"063 AS ‘]80
"093 “269 vkge2
OA OD Syd 160
corresponds to a different external resistance. 7, is the current,
in amperes, given by the generator, 2 that indicated by the
hot wire close to the discharge, and 2, the effective alternating
current, which in one ease is nearly three times as large as the
direct current supplied.
(ec) If a coil of moderately large self-inductance is con-
nected close to the tube on each side, the discharge becomes
irregular and noisy, and no high-frequency oscillations appear.
There seems to bea critical value of the self-inductance at
which the oscillations suddenly cease. The cessation of
oscillations apparently shows that the glow-are pulsations
cannot take place above a certain frequency.
(7) Hold one terminal of an incandescent lamp of high
resistance in the hand, and touch the other terminal to the
discharge circuit near the tube. The lamp lights up, the light
being brighter when the lamp is on that side of the tube nearer
to a self-inductance, as it is here that the antinode of the
e.m.f. wave occurs.
(g) By means of a frequency meter with a range of from
0: 25610 to 510° periods per second, the fundamental vibra-
tion and its upper harmonics can be detected. The best
method is to allow a coil of a few turns in the discharge
= ae on
5 :
a:
rs
W. @. Cady—Electric Arc between Metallic Electrodes. 248
cireuit to act inductively on a second coil in fairly close coup-
ling with it. If the second coil is in series with a small lamp
and a variable condenser, then as the capacity is slowly varied
the lamp can sometimes be seen to light up three or four times,
as successive harmonics are passed. The lamp sometimes glows
more brightly than a similar one in the discharge circuit.
(A) It the coupling in the last experiment is close, then on
closing the resonating circuit it is found that the direct current
from the generator is reduced, showing that the secondary
cirenit has reacted on the primary.
$19. Energy and efficiency of the oscillations.—The follow-
ing experiment was performed in order to discover how large
a percentage of the direct current energy expended in the
oO
discharge could be converted into the energy of electrical
oscillations. Two 4candle power 110 volt incandescent lamps
of about 700 ohms resistance each were connected in the dis-
charge circuit, one on each side of the tube. They absorbed
nearly all the energy of the oscillations, and glowed more
brightly when the discharge passed than when the electrodes
were touching.
The total power absorbed by the lamps is given in the first
column of Table II. It was estimated from the brightness of
TaseE II.
Watts in lamps Watts supplied Per cent Generator
as2ls -d:. ca. c. to are efficiency current
fa6 p4.. 84 18°0 46 06 te
19°6 we bo2 Pid Sheva epee O72
25°0 =O: -16°0 24°2 66 OS 2F us
36°0 20°4 15°6 34°5 45 oI ZoArect
the lamps. In the second column are recorded the watts
expended in the lamps by the direct-current component,
obtained by multiplying the square of the generator current
(last col.) by the lamp resistance. The difference between the
first and second columns gives the watts of alternating current
power consumed by the lamps. The watts supplied by the
generator to the discharge (neglecting the external resistance)
are given in the fourth column, while the fifth column shows
the ‘efficiencies, obtained by dividing col. 3 by col. 4. It
will be observed that the highest efficiency recorded is 66
per cent.
§ 20. Determination of the frequency.—The following
resonance method was used in determining the Trequency of
the oscillations. In the main discharge cireuit, about 30-50™
from the tube, was a coil of wire which in most of the experl-
ments conced of six turns, having a diameter of 22°. Its
244 W. G. Cady—Llectric Are between Metallic Electrodes,
self-inductance was about 20,000™. This primary coil acted
inductively on a secondary coil at varying distances from it.
The secondary coils used had self-inductances varying from
qo0e" to A OL00 Ou:
In series with the secondary coil was an adjustable condenser
of zine plates separated by sheets of glass, the whole immersed
in kerosene. The secondary circuit contained also a hot-wire
ammeter of about two ohms resistance. As detecting devices
a thermo-element, and also a bolometer in a tertiary cireuit
loosely coupled with the secondary circuit, were tried, but
neither method gave as good results as the hot wire in the
resonating circuit itself. For the purpose in hand, the damp-
ing caused by the resistance of the hot wire was not serious.
According to the method just described, it will be seen that
the e.m.f. induced in the resonating circuit is proportional to
the current in the discharge circuit. That is, if J/7 represents
the mutual inductance between the two coils,
ee
7a dt”
Since this expression involves the frequency, it follows that
é, = kis, (1)
where £# is a constant.
By using secondary coils of varying self-inductanece and each
time adjusting the capacity for resonance, the fundamental
vibration together with its upper harmonics could be investi-
gated for frequency, and to some extent for intensity. It was
always found that the hot-wire deflections corresponding to the
fundamental vibration were very small. This agrees with
the relation expressed in equation (1), since f has its smallest
value for the fundamental, and the hot-wire deflections are
proportional to the square of e,. Remembering also that the
wave-torm of the oscillations is certainly very complex, it is
evident that the deflections corresponding to some of the upper
harmonies will be much greater than those for the funda-
mental. I found it necessary to use very close coupling in
order to detect the fundamental at all. Loose coupling could
be used for harmonies from the third to the ninth, while above
that the coupling had to be made close again, on account of
the diminishing value of 2,.
SAL When the capacity of the discharge circuit was
increased by touching a piece of metal about 10 square to a
point near the discharge tube, the frequencies were slightly
lowered, as would be expected.
§ 22. Introducing a coil of a few turns of wire into the
discharge circuit lowered the frequency. A coil of larger
W. G. Cady—EHlectric Arc between Metallic Hlectrodes. 245
self-inductance greatly increased it, since the penetration of
- the oscillations was stopped by reflection from the coil.
§ 23. Varying the supply e.m.f. from 600 to 1000 volts had no
effect upon the intensity or frequency, as long as the current
remained unchanged. eversing the direction of the current
also had no effect.
§ 24. Increasing the current increased the frequency, as
illustrated in the following table, in which the last column
TasxeE III.
Generator
current Frequency Deflection
0°09 amp. Somos 49m"
Oe HORS 8:7 Ee 104
Ove kal alee Cae ee 109
Osl3 <5" 9°3 ES 56
elisa. 16 9°45 ok 39
gives the hot-wire deflections, serving as a measure of the
intensity of the oscillations. The frequency observed is that
of the third harmonic. If the intensity of the oscillations
diminished with increasing current, it would be possible to
account for the increase in frequency on the supposition that
with decreasing imtensity the oscillations penetrated less far
into the circuit, i. e. that the effective length of the “oscilla-
tor” was less. But the third column shows that the intensity
was greatest for a current of 0-11 amp., and diminished as the
current increased or decreased (§ 8). The change in frequency
must be due to the changing resistance of the heated vapor,
which affects the frequency according to the formula
vl / l R*
Meo NG GAL?
An increase in the discharge current, decreasing the resistance
f? between the electrodes, must clearly raise the frequency.
The apparent mean resistance, derived from the measurement
of current and e.m.f., varies under different conditions between
2000 and 5000 ohms. It is hardly conceivable that the resist-
ance for oscillations can be as high as this, but it is evident, at
least, that the discharge possesses a high resistance, which
changes markedly as the current is varied.
As no means suggested itself for measuring directly the
resistance of the discharge for oscillating currents, I tried the
effect of inserting a large known non-inductive resistance
(graphite rod) in the circuit close to the discharge. This
experiment failed to throw light on the problem, for when the
resistance was large enough to modify the frequency at all, it
absorbed the oscillations and reduced their penetrating power
to such an extent that the frequency was increased instead of
decreased. The resistance of the discharge would not be
Am. Jour. Sct.—Fourta SERIES, VoL. XXVIII, No, 165.—SrpremsBer, 1909.
AS!
246 W. G. Cady—Electric Arc between Metallic Hlectrodes.
expected to limit the penetration of the oscillations to a like
extent, since the discharge is the source of the oscillations and
they are propagated in each direction from it.
It was difficult to determine the effect on the frequency of
varying the length of the discharge, for this length was limited
by the available e.m.f. to about one millimeter, and it became
continually shorter as the discharge passed, on account of the
deposits of carbon dust on the electrodes. One would expect
an increase of length to cause an increase in resistance, and
thus to diminish the frequency of the oscillations. It can only
be affirmed that the possible variation in length was over too
small a range to affect the frequency appreciably.
$ 25. Systems of harmonics.—Owing to the impossibility of
keeping the state of the discharge and intensity of current
constant long enough to obtain data for a full resonance curve,
only incomplete groups of harmonies can be shown, obtained
at different times, and under different conditions. The dis-
charge, and consequently the frequency, fluctuated so much
that the resonance curves were considerably flattened, as if the
oscillations had been damped. But in one or two signal
instances (see § 29), when the discharge was unusually steady,
curves for one.or two frequencies of great sharpness were
obtained.
In the following table some representative groups of har-
monic frequencies are shown. The figures in the first two
Tasue IV.
Observed No. of
Fundamental frequency Ratio harmonic
( 0°25 0°98 1
| 0°465 1°82 2
pees 1°02 4°0) 4
Oe? 4 1:32 5:18 5
ise fol 7
| 2°22 8°70 9
( 0°237 IO) il
| 174 Omoal 6
0°237 { 1°68 TAO 7
P29) Wee 12
aed 15°6 16(?)
( 0°46 2°09 2
| 0°66 3°00 3
2
eee 1 0-84 3°83 4
(like 5°09 5
( 0°87 3°02 3
Palais: 4°10 4
0°288 sla 5°90 6
| 2°30 Aa) 8
| 2°88 10°0 10
W. G. Cady—FElectrie Arc between Metallic Electrodes. 247
columns give the frequencies in millions per second. The har-
monic relation is in general clear, considering that in many cases
the settings were difficult and resonance ill-defined. The value
of the fundamental given in the first column is that which best
satisfies the observed upper harmonics. Owing to the loose-
ness of the coupling, the fundamental could not be directly
observed in all cases. As a test of the accuracy, the third col-
umn contains the quotients obtained by dividing the observed
frequencies by the fundamental. These quantities should be
integers representing the number of the harmonic.
The differences between the wave-forms of the various
groups are due to differences in current and changes in the
electric circuit.
ies 2
al es |
Nefopo to pe eee ey ae
PEER REEE EE EHP Det Pe
§ 26. The results of the last group are also represented in
fig. 2, in which the resonance curve is drawn. All the obser-
vations were made within the range of the adjustable con-
denser, the same secondary coil and the same degree of coup-
hing being g preserved for all. The ordinates are not observed
deflections of the hot wire, but are in arbitrary units propor-
tional to the intensity of the primary oscillations, derived from
the formula
C me Ses
z, — 7 V4,
in which 2, is the effective value of the harmonic in question,
J the frequency, d the hot-wire deflection, and ¢ a constant.
The deflections are thus corrected for frequency (§ 20) and for
the parabolic form of the hot-wire relation.
§ 27. Perfect agreement between the different harmonics in
each group cannot be expected, as indeed other observers have
found that not all the harmonic frequencies in electrical
248 W. G. Cady—FHlectric Arc between Metallic Electrodes.
oscillations are integral multiples of the fundamental. More-
over in the present case it is not impossible that some one por-
tion of the circuit, whose natural period is not far from that
of one of the harmonics, may introduce a disturbing element.
§ 28. By using in the resonating circuit a coil of very small -
self-inductance, frequencies have been observed as high as nine
million. This must be a harmonic of the order of the thirty-
sixth, unless it is due simply to a small portion of the discharge —
circuit in which feeble oscillations of very high frequency
were excited. :
§ 29. Are the oscillations undamped ?—A satisfactory answer
to this question cannot be obtained from most of the resonance
curves. Some of the curves examined, including that in fig. 2,
gave as the sum of the decrements in the primary and second-
ary circuits values ranging as high as 0°124. As the secondary
decrement could be computed from the constants of the con-
denser circuit, the apparent decrement of the primary oscilla-
tions was found by subtraction. This gave, in the ease of the
curves referred to, primary decrements of from 0-07 to 0°10.
But on other occasions, when the discharge consented to take
place steadily for a sufficiently long time, sharply-pointed reso-
nance curves were obtained, showing a primary decrement no
larger than 0:005.
It looks as if the glow-are oscillations were of themselves
undamped, the flatness of the curves being caused by the con-
tinually fluctuating frequency and intensity. If, on the other
hand, the discharge were a succession of true sparks, one would
expect the damping to be greater and the higher harmonies
less pronounced. |
There is much similarity between the production of these
oscillations and those studied by M. Wien for the generation
of undamped oscillations by “Stosserregung.”* The essential
differences are made clear in §§ 9, 10, 18, and 14. Moreover,
in Wien’s method the damping of the secondary circuit must
be small in comparison with that of the primary. Although
we do not know the resistance of the discharge-gap to the
oscillations described in this paper, still the evidence of the
resonance curves points to a larger damping in the secondary
than in the primary cireuit.
$ 30. Quantity of matter liberated from the cathode per
oscillation.—During oscillations, the anode is not perceptibly
attacked. The cathode wastes away so slowly that it seemed
worth while to ascertain how small a fraction of a gram is
volatilized each time the discharge is on the arc phase. The
oscillations were accordingly allowed to pass as continuously
as possible for one hour, the current being 0°12 amp., funda-
* M. Wien, Ann. Phys., xxv, p. 625, 1908.
W. G. Cady—FElectric Arc between Metallic Electrodes. 249
mental frequency about 240,000. The loss in mass of the
copper cathode was 0°018 gram. corresponding to a loss per
period of 21X10-" gram. This is the mass of about
3°5 10" atoms of copper.
§$ 31. Oscillating system in parallel with the discharge.—
It seemed of interest to try the effect on the discharge of con-
necting in parallel with it a capacity and self-inductance. I
have not been able to obtain anything except oscillations of the
Duddell type under these conditions, in fact the glow-are
oscillations seemed much diminished in iutensity, while the
direct current of the supply increased on closing the condenser
circuit. The discharge became steadier and more like a stable
are Im appearance.
§ 32. Radiation of energy from the discharge circuit.—
With a discharge between copper terminals in air, giving
oscillations feeble and of low frequency in comparison with
‘those later used, an ordinary telephone receiver emitted a
rustling sound when held more than a meter distant from the
discharge. The receiver was connected between two straight
wires, each 60°" long, terminating in tin sheets 10™ square,
which served as a detecting system.
From the same discharge, radiations were transmitted to a
bolometer four meters distant. They were greatly strengthened
by placing a large concave mirror behind the discharge.
Using the stronger oscillations of our later experiments, the
bolometer was found to respond when 35 meters away from
the discharge circuit. The discharge current itself was carried
vertically up the outside of the laboratory for a distance of
twelve meters, the circuit being completed inside the building.
The energy radiated from this “aerial” was received by a
second aerial nine meters high at a neighboring house, and the
bolometer was connected between this and the or ound.
SUMMARY.
1. The apparatus is described for producing glow-are oscil-
lations of high frequency. Either alternating or direct e.m.f.
may be used.
2.-A number of experiments are described, using incandes-
cent lamps or hot-wire ammeters, demonstrating some of the
effects of these high-frequency currents and their upper har-
monics.
Under favorable circumstances 66 per cent of the energy
Sted to the discharge can be converted into oscillating
currents.
4. The frequency of the fundamental wave observed in
most cases was of the order of a quarter of a million.
250 W. G. Cady—Electric Are between Metallic Electrodes.
5. The effects of varying the capacity, self-inductance, and
current of the discharge circuit are described.
6. By means of a tuned resonating circuit the presence and
relative intensities of a large number of high harmonics were
ae
Observations of damping were carried out with difficulty,
but they indicate that the oscillations are undamped.
8. The quantity of matter volatilized at the cathode on the
are phase per cycle was measured.
_ 9. When a capacity and self-inductance are connected in
parallel with the discharge, the oscillations are diminished.
10. Experiments are described that illustrate the radiation
of electromagnetic waves from the discharge and from the por-
tions of the circuit adjacent to it.
Erratum.—tIn the second paper, page 97, line 32, for
OD ane.” ada) 9 Bs euTaid.”
Scott Laboratory of Physics,
Wesleyan University, June 11, 1909.
Hull—Initial Velocities of the Hlectrons. Po
Art. XXVI—TZhe Initial Velocities of the Electrons
Produced by Ultra- Violet Light; by Aubert W. Hott.
[Contributions from the Sloane Physical Laboratory of Yale College. ]
Lenard* was the first to investigate the initial velocities
with which electrons are shot out by a metal plate illuminated
by ultra-violet light. He found that the velocities varied with
the nature of the illuminated metal and the source of light,
but were independent of the intensity of the light, from
which he concluded that the effect must be due to reso-
nance, but that the greater part of the energy of the electrons
must come from within the atom, ‘the resonance playing only
a releasing role.” Ladenburgt investigated more carefully the
nature of this resonance effect,and found that, for a given
metal, the maximum velocity of the electrons emitted was
directly proportional to the frequency of the incident light.
More recently Ladenburg and Markant{ have shown that, for a
particular spectral region, all the electrons liberated have
velocities lying between narrow limits, and they conclude that
each wave-length liberates electrons whose frequency of vibra-
tion has a definite relation to that of the light, and whose
initial velocities are, therefore, either all equal or grouped
closely about a mean.
The range of wave-lengths used by these investigators was
from 2 2000 to » 2700. The importance of the results makes it
desirable that they be verified for a wider range. The present
paper contains an account of experiments on this subject in
the region of short wave-lengths discovered by Schumann.
The general method is the same as that used by Lenard and
by Ladenbure and Markau. The source of ight was an inter-
pal capillary dischar ge tube of the type used by Lyman§ in his
spectroscopic work, filled to about one millimeter pressure with
hydrogen or carbon dioxide, and closed by a fluorite plate.
Different wave-lengths were obtained by interposing various
absorbing screens between the discharge tube and the photo-
electric chamber.
Betore describing the final experiments, a word should be
said about some attempts which were unsuccessful. Using the
method of auxiliary field employed by Ladenburg and Markau
for preventing reflegtion of electrons, with an apparatus
exactly similar to that shown in fioure 4 of their paper, | the
*P. Lenard, Ann. Physik., ii, p. 359, 1900; viii, p. 149, 1902.
+ E. Ladenburg, Phys. Zeitschr., viii, p. 590, 1907.
¢ Ladenburg and Markaun, ibid., ix, p. 821, 1908.
$T. Lyman, Astrophys. J., xxiii, p. 189, 1906.
|| Ladenburg and Markau, loc. cit.
O52 - Hull—Initial Velocities of the Electrons.
author was unable to get results comparable with theirs. The
current of electrons increased continually and rapidly with the
potential difference between the illuminated plate and gauze,
until the latter reached about 40 volts. From this point on
the current remained practically saturated, showing that the
lack of saturation at lower potentials was not due to an insuf-
ficient vacuum. It might be explained by the assumption that.
the photo-electric radiation of electrons, even from a polished
plate, is diffuse, as Lenard showed it to be from a plate covered
with lampblack. But this assumption would not explain the
saturation observed by Ladenburg and Markau. |
The method finally adopted was the following: Light from
an internal capillary discharge tube passes through a screen
3 eell C (ig. 1) 1° ame lenenhe
Gaya : :
closed by fluorite windows,
through the limiting dia-
phragms @ and 6, and falls
on the insulated electrode A.
to electrometer , 4 a orl pump A is supported by a stem
~ Wo - which passes through amber
Nea 10 plugs in the brass tube ¢,
, bobattery, is sealed into the glass tube
= & by amber and sealing wax,
‘Lo meycuvy pump| | and connected to a Dole-
C zalek electrometer. The
diaphragms @ and 6 are con-
a. nected to the brass cylinder
| b B, which is insulated and can
ne B be charged to known poten-
a tials. All parts of Band A
A are covered with lampblack
from anacetylene flame. In
the lower end of the glass
BER tube containing the elec-
CO 8S°S trodes is 10 grams of cocoa-
Nowe a) 7) nut charcoal, which is heated
eS while the tube is being
| exhausted, so that after cool-
ing the pressure is ‘001™™. The tube is then sealed off from
the pump, and immersed in liquid air above the level of the
cylinder 6. Diffusion of gas out of the lampblack on the
electrodes is thus prevented, and a high vacuum assured.
To determine the initial velocities of the electrons, B is
charged to small negative potentials, and the current between
A and B measured by the electrometer. Only those electrons
whose initial kinetic energy, divided by their charge, exceeds
the potential difference between A and B will be able to escape
253
Hull—Initial Velocities of the Hlectrons.
Fies. 2, 3, 4.
‘T 9AIND YIM OplOUOO BUITXVW ILoy} Jey OS peyLuseM ore “F “Sy UL [IT pue TJ] seaino pure ‘e puv g ‘Sey UI T] SaaINo oyy JO sezBUIpsO oq,
‘Ulu ted VW utory Suideose AjLoLIYoaTe “sou Jo Ay yuUeNb oy) soyeUIpIo ‘gq puke YW UWeeMj0q oolLetIIp [eyuUsjod yueserder s¥esslosqW
aE. de. eee
)
‘ ¢
(D)
:
—
0
0 |
PE
| Ap
i
= ee
tliat
a
j,
= = eee. ZZ)
= a |
|
|
| zd 2 ps 5
|
A) a a ae
al
oy) os oh
254 Hull—-Initial Velocities of the Electrons.
from A. Hence the electrometer deflections will be propor-
tional to the number of electrons whose energy per unit
charge* exceeds the corresponding potential of B. The
maximum energy possessed by any of the electrons will be
that potential which is just sufficient to prevent any of them
from escaping, and is given by the point where the curves in
figures 2, 3 and 4 become tangent to the straight line represent-
ing the constant negative leak due to reflected light. From the
values of the energy the velocity can at once be determined
Ace €
by substituting the known value of —.
70
The experiment was first tried with hydrogen in the dis-
charge tube. When the screen cell C is exhausted, the hydro-
gen discharge throws upon A light of all wave-lengths down to
A 1230, the limit of transparency of white fluorite. Filling
the cell with air at atmospheric pressure cuts off practically
everything below 11710. In this way two definite spectral
regions are obtained, and since the effect without air in the
screen cell is 25 times as great as with it*that is, the electrons
produced by the hydrogen light of longer wave-length than
A1710 are only 4 per cent. of the total, this region of shorter
wave-lengths may be taken to extend from A 1230 to A 1710.
The results are given in Table I and figure 2. The ordinates
of curve IJ are magnified so that their maximum, representing
the total number of electrons set free by the light, coincides
with that of curve I. While the two curves show a somewhat
different distribution of velocities, indicating a larger propor-
tion of high velocity electrons for the light ol higher
frequency, the maximum velocity is the same for both.) 1
appeared from this that the proportionality, discovered by
Ladenburg, between the velocity of the electrons and the
frequency of the light producing them, did not extend to these
short wave-lengths. For the shortest wave-length in the
unscreened light was estimated to be 2X 1230, that in the
screened light 7 1710, so that the maximum velocities should
have been very different in the two eases. :
As a variation of the experiment the discharge tube was
filled with carbon dioxide, and now a different result was
obtained. There was a very marked difference in the maxima,
as is shown in the second part of Table I and figure 3. | With-
out the air screen the maximum energy of the electrons is
about 3°3 volts, with the sereen only 2°5 volts. If the shortest
wave-length in the spectrum of carbon dioxide is taken as
* For the sake of brevity, the energy per unit charge will hereafter be
designated simply as energy of the electrons.
+See T. Lyman, Astrophys. J., xxv, p. 45, 1907.
i See i. Lyman, ibid. /xxvii,p. 87, 1908)
Hull—Initial Velocities of the Electrons. 255
Tasie I,
Loss of Neg. Electricity by A.
Coulombs per min. x 10~§
——-H, Light- ant ——--CO, Light--———
Pot. of Without air With air Without air With air
B volts screen screen screen screen
—6 —2 —0°'072 — 0°27 —0°065
—4 —1°5 —0°059 —0°23 De aes
—3°5 — 1°25 eGo a ng KE
—35°0 — 6°05 0°002 —0°17 ear
—2°5 2°0 0:077 —0'08 —0°0638
—20 ey 0°185 0°38 —0°041
—1°5 ete, 0°340 Leh 0°039
—1°0 20°8 0°640 2°59 0°367
—0°5 30°5 aa 4°95 leis
Q. 39°8 1:99 7°00 2°09
+ 0°5 A 2D 7°53 BAAS
+1] 42°5 pi 5) 7°62 Deane
2 43°6 21 Meow 223
+4 45°0 Lo) 7°66 Deal
+6 44°0 Dyes eS) 7°63 2°33
about 1480, and the limit of the absorption of air as A 1107,
then the inverse of these wave-lengths are proportional to the
maximum velocities, that is, to the square-roots of the maxi-
mum energy given above, which fits Ladenburg’s hypothesis.
This suggested that the results with hydrogen hght might
be explained by a small amount of light of very short wave-
length getting through the air im the screen-cell. Lyman *
has shown that the absorption of air is in the form of a band,
which, for a column of air 0°91 long at atmospheric pressure,
extends from about A 1710 to A 1270. The more refrangible
limit of the band is so indistinct on a photographic plate
that Schumann was unable to detect it at all.t But the
photo-electric effect is probably more sensitive than a photo-
graphic plate, especially for the shortest wave-lengths, since, as
Ladenburg has shown, it increases very rapidly with decrease
in wave-length. Moreover the ordinates of curve II in figure
2 are magnified twenty-five times. Hence a very small amount
of light between A 1270 and X» 1230 might produce enough high-
velocity electrons to change the form of the lower part of
curve II, and since the shortest wave-length, 1230, is the same
as without the air screen (curve I), the maximum velocity
would be the same for both.
To test this point the discharge tube was disconnected from
the fluorite cover of the screen cell C, and closed by a separate
*T. Lyman, Astrophys. J., xxvii, p. 108, 1908.
+ Schumann, Smithsonian Contributions, No. 14138.
256 Hull—Initial Velocities of the Hlectrons.
fluorite plate. It was then adjusted in a vertical position so
that it could be raised enough for a quartz plate, 1:°5™™ thick,
to be placed between it and the cell C. Lyman* has shown
that quartz of this thickness absorbs all light below X 1450.
The results with the quartz are given in Table IT and figure
4. The absolute values cannot be compared with those in Table
I, since the intensity of the light was not the same. The
scale of ordinates of the different curves in this, as in the pre-
vious figures, is so chosen that their maxima coincide. Curve
I, which gives the velocities without the quartz and with the
cell C evacuated, is the same as curve I in figure 2, and is
Tasue II.
HI, Light
Loss of Neg. Electricity by A.
Coulombs per min. x 107°
Pot. of B 16mm 1.9m
volts Quartz screen Quartz + 1°5™ air
—6 —0°88 —0'0384
—4 —0'79 —0°036
—3 —O'78 —0°031
—2°5 —0°285 —0'030
— 2:0 1°52 —0'029
—1°5 ra yero 5) 0°:009
—1'0 1223 0°223
—0'd 21°D 0°845
0) 374 1°86
+0°5 semen pate
+1°0 40°3 24
+2°0 42°] . 2 ae
+ 3°0 Aas eee ZA
+4:0 49°5 AD'S)
+6°0 43°8 Oley
inserted here for comparison. It shows a maximum energy of
about 3°5 volts, produced by light of > 12380. Curve II,
obtained with the quartz, but no air in the screen cell, gives
a maximum energy of about 3 volts, which must be due to
light of > 1450-1500, the limit of transparency of quartz.t
Curve III shows the effect of both quartz and air screen. It
represents the same conditions as curve II in figure 2, except
that the small amount of light between > 1270 and A 1280 has
now been cut out by the quartz. The maximum energy is
now about 2°4 volts, which niust be due to light of » 1710, the
less refrangible limit of the air absorption band.
*T. Lyman, Astrophys. J., xxv, p. 49, 1907.
+ Lyman’s photographs show that the absorption of 2™™ of quartz is com-
plete below about 4 1500, that of 0°2™™ below 4 1450. The limit for 1°5™™
will be between these values.
Hutl—Initial Velocities of the Electrons. 257
The exact values of the maximum energy are hard to
determine, but the points of zero deflection of the electrom-
eter, where the curves cut the axis of abscissas, can easily be
determined to within 0:01 volt, and since it is probable that
the same proportion of light is reflected in each experiment,
the potentials represented by these points will be nearly pro-
portional to the real maxima. ‘These values will therefore be
used in testing the proportionality between light-frequency
and the velocity of the electrons, and are designated in Table
III as maximum energy.
If the results of Ladenburg hold for this region, the maxi-
mum energies and the shortest wave-lengths in the light pro-
ducing them should be related according to the equation
x x = /V, : ./V2, where V is the energy in volts. If
we take as a fixed point of reference the shortest wave-length
in the hydrogen spectrum which can get through white fluor-
ite, % 1230 as determined by Lyman, to which corresponds
the maximum energy, 3°03 volts, the other wave-lengths can
then be calculated by the formula
21930 1 ae
V
and the calculated values compared with those which are
known from spectroscopic experiments. This has been done
in Table ILI.
diesrorod OO E
——-Shortest Wave-length-——,
Maximum Calculated Estimated
Source Energy on from
of in Ladenburg’s Spectroscopic
Light Screen volts Theory Experiments
H, eS: 9™m fluorite 3°03 [1230] 1230
CG: 2™™ fluorite 2°49 1375 above 1230
H, ie 1°5™™ quartz 230 1400 1450-1800
fies 2 bb quartz
Seo ear St, V7 LO » ane
Co. Ly aie 162 1680 1710
(or a little less)
In regard to the values of > in the last eolumn, those for
hydrogen, taken from Lyman’s results with the vacuum spec-
trograph, may be regarded as well fixed, although some of
them may be too high for the photo-electric effect, which is
probably more sensitive than a photographic plate, especially
in the region of very short wave-lengths. This may account
for the low value obtained with quartz.
258 ITull—Initial Velocities of the Electrons,
In the case of carbon dioxide, all that I have been able to
find about the emission spectrum in this region is the follow-
ing statement by Schumann:* “Its photographic action is
uncommonly strong, and it extends far beyond 162 into the
region of the shortest wave-lengths. I doubt not that, were
the tubes sufliciently transparent, it could be photographed as
far as the hydrogen spectrum extends. [or its wealth of lines
it stands unrivalled.” From this statement it appears that,
whatever the cause, the spectrum of carbon dioxide photo-
graphed by Schumann did not extend quite as far as the.
hydrogen spectrum. The value » 1375 is, therefore, a very
reasonable one.
The less refrangible limit of the air absorption band should
be about the same for carbon dioxide as for air, except that it
might be a little lower for carbon dioxide, owing to its “ wealth
of lines” in this region.t The results seem to indicate that
this is the case.
The agreement is, therefore, as good as our present knowl-
edge of absorption in this region will warrant. For the two
cases where this knowledge is most accurate, namely the limit
of the hydrogen spectrum due to the absorption of white fluor-
ite, and the less refrangible limit of the air absorption band,
the agreement is remarkably good.t An exact comparison of
these results with those obtained by Ladenburg for longer
wave-lengths is impossible, owing to the difference in method
and in the nature of the illuminated metal. In Ladenburg’s
apparatus there was very little light reflected to the receiving
wires (corresponding to our electrode B). Hence his maximum
velocities correspond more nearly to the real maxima defined
above than to the relative maxima of Table III. The metals
investigated by Ladenburg were platinum, copper, and zinc,
and for > 2010, his shortest wave-length, he found as maxti-
mum energy : for platinum, 1°86 volts; for copper, 1°69 volts;
for zine, 1:12 volts; and he observed that the energy was
greater the more electro-negative the metal was. If this order
holds in general, the maximum energy for carbon for X 2010
should be between 1°86 and 1°69 volts, and for » 1710, extra-
polating on Ladenbturg’s hypothesis, it would be between 2°57
and 2°33 volts. The value of about 2°5 volts found above for
X 1710 lies between these limits. The agreement is, there-
fore, qualitatively correct.
The question of velocities between zero and the maximum
requires further investigation. The fact that a positive poten-
* V. Schumann, Smithsonian Contributions, No. 1418, p: 16.
+ ilydrogen gives only a weak continuous spectrum between 4 1675 and
A 3700. Lyman, Astrophys. J., xxiii, p. 199, 1906 ; Schumann, 1. c. p. 28.
¢ The exact agreement is of course accidental.
Hull—Initial Velocities of the Klectrons. 259
tial of about one volt on B is required to enable all the elec-
trons produced on A to escape is probably due to two causes.
(1) Reflection of the electrons from B. O. v. Baeyer* has
shown that even a lampblack surface reflects diffusely about
ten per cent of the electrons which strike it. The better satu-
ration obtained by Ladenburg and Markau may be explained
by the fact that their apparatus had a blackened wire gauze in
front of the lampblacked surface corresponding to B, which
still further lessened the reflection.
(2) Entanglement of the diffusely radiated electrons by the
rough surface of the blackened radiator A. If a blackened
surface so entangles the electrons which strike it as to prevent,
in a large measure, their reflection, it is probable that it also
hinders, to some extent, their escape from the illuminated plate.
The question whether the electrons liberated by light of a
particular wave-length are all of one velocity or of several
velocities is of great importance to the theory of the photo-
electric effect, and the author proposes to extend the work of
Ladenburg and Markau on this subject to the region of shorter
wave-lengths.
Before concluding, the author wishes to express his thanks
to Professor Bumstead, at whose suggestion this investigation
was undertaken, for his interest in the work, and to Professor
Boltwood for many valuable suggestions.
Summary.
The initial kinetic energy of the electrons liberated from
earbon by light between A 1710 and A 1230 has been measured,
and the proportionality, discovered by Ladenburg, between
the maximum initial velocity of the electrons, 1. e. the square
root of their maximum initial kinetic energy, and the fre-
quency of the hght producing them, has been found to hold
for these short wave-lengths, to the degree of accuracy with
which this part of the spectrum is known. It may now be
stated that, for the entire range, X 2700 to »X 1230, the initial
velocities of the fastest electrons liberated by light of particu-
lar frequencies are proportional to these frequencies. The
question of the production of electrons other than the fastest
will be further investigated.
*O. v. Baeyer, Phys. Zeitschr., x, p. 181, 1909.
260 C. O. Hutchins—New Declination Instrument.
Arr. XXVII.—A Wew Declination Instrument; by ©. C.
. Hortcurs.
Tue declination is the only magnetic element that the
engineer and navigator wish to know, and it is hoped that the
apparatus to be here described will be found as useful and
much more simple than commonly employed in finding it.
Reference to the figure will make the following details plain.
We have a telescope of l-inch diameter and 6-inch focus.
Upon the telescope tube are two carefully turned bronze rings
upon which the telescope rests in a light cradle C-D. The
cradle is suspended with floss silk from a torsion-head H.
The telescope hangs in a box upon which are mounted two
level phials. One side of the box is of glass and is removed
by a convenient knob K. | ‘
A rod runs the length of the box and bears two hook-like
supports A-—B. When the rod is revolved by means of a
lever at the eyepiece end, and the lever slipped over a catch
at O, the supports then lift the telescope from its cradle and
support it. The eyepiece of the telescope projects through
one end of the box, where it is covered with a cap to protect
it from air currents. Before the objective is a plate-glass
window. |
The whole is mounted upon a small divided circle reading
to minutes. The socket of the circle may be made to fit the
ordinary engineer’s tripod.
The peculiarity of the apparatus lies in the telescope, whose
tube is made of steel and is magnetized. It was found that a
very satisfactory tube could be made by case-hardening a piece
of ordinary bicycle tubing, and magnetizing. The eyepiece of
the telescope has a single wire at its focus.
The operation of the instrument is as follows :—
It is set up on a meridian line. About 200 feet away, and
in the approximate direction of the magnetic meridian, is
placed a horizontal scale divided to inches, with bold marks.
The telescope being removed from the box, a brass tube of
the same weight is substituted, and the torsion head is rotated
until the suspension is free from torsion. The telescope is
replaced and the box being rotated until it points to the dis-
tant scale, the excursions of the vertical wire are observed,
and its point of rest found in the usual way. This observation
is repeated after rotating the telescope 180° in its cradle.
This eliminates the effects of parallax and the lack of coin-
cidence of the magnetic and telescopic axes.
The mean of the two points of rest is found; the telescope
261
C. C. Hutchins—New Declination Instrument.
inte
URTH SERIES, VOL. XXVIII, No. 165.—SEpTEMBER, 1909.
18
Am. Jour. Sct.—Fo
262 C. C. Hutchins—New Declination Instrument.
lifted from the cradle to the supports A-—B and the circle
rotated until the eyepiece wire marks the mean point of rest.
The circle is now read, and a pointing being made upon the
meridian mark, the change in the circle reading is the declina-
tion sought. The declination is rarely wanted closer than the
nearest minute, in fact considering the rapidity with which it
changes is not obtainable to less than that amount, and experi-
ence has shown that an apparatus of the above dimensions is
needlessly large for that degree of accuracy.
A telescope of four inches length would doubtless do as
well, and thereby the whole would become very compact and
portable.
Bowdoin College, June 14, 1909.
EF. S. Larsen—Relation between the Refractive Index, ete. 263
Arr. XX VITI— The Relation between the Refractive Index and
the Density of Some Crystallized Silicates and Their
Glasses ; by Esprr 8. Larsen.
Investicators have long sought to discover a simple relation
between the index of refraction of a substance and its density
which is independent of the temperature and alse valid even
when the substance is mixed in solution with other substances.
Laplace* early derived the relation
— = constant 1
ae (1)
from a consideration of Newton’s emission theory of light.
This formula did not satisfy later experimental data and in the
middle of the last century Gladstone and Dale derived the
relation :
nm— 1
d
which they called the specitic refractive energy. Theoretically,
this formula is based upon the assumption that the molecules
in the line of transmission of a given light wave retard that
wave by an amount which is independent of their arrangement
and distribution along that wave. Their own statement is :+
“ Every liquid has a specific refractive energy composed of the
specific refractive energies of its component elements, modified
by the manner of combination, and which is unaffected by
change of temperature, and accompanies it when mixed with
other liquids. The product of this specific refractive energy
and the density is, when added to unity, the refractive index.”
More recently, Lorentzt and Lorenz, on the basis of the
electromagnetic theory of light, independently derived the
relation :
= KK, where # is a constant (2)
fies ee |
° - — K 3
Fy ee I) OG i)
The specific refractive energy being an additive property, we
may immediately write the relation,
y
K, =k & 4
where & is the specific refractivity of the mixture and & that
of any component, while p is the weight per cent of that com-
-*Traité de Mécanique Céleste, IV, x, 232.
+ Phil. Trans., 357, 1863.
t Wied. Ann., ix, 641, 1880. § Ibid., xi, 70, 1880.
264 £. 8S. Larsen— Relation between the Refractive Index
ponent present. We can apply this formula to the elements
making up a compound as well as to a simple mixture or solu-
tion. An identical relation holds for the formula of Lorentz
and Lorenz:
= )
K, = kh, + (5)
Since the appearance of the papers of Gladstone and Dale,
much work has been done to test their formula and several
other formule have been proposed, but only those of Glad-
stone and Dale and of Lorentz and Lorenz have theoretical
significance or general application. Both formule, together
with the corresponding formule for dispersion and for the
additive relation for solutions and the elements of a compound,
have been caretully tested on many organic liquids and salt
solutions. In general, the two formule hold almost equally
well for varying temperatures and concentrations, the first
holding better in one case and the second in another. Lorenz,*
Bruhle,+ and others have shown that when applied to a sub-
stance in different states,—to a gas and a liquid, for example—
the simpler formula gives errors as great as thirty per cent,
while the »* formula gives lower though still considerable
errors. Landolt,t Conrady,$ and other investigators showed
that in organic liquids the refractive constant depends upon the
atomic constitution as well as upon the chemical composition,
and that some elements, such as oxygen, must be given differ-
ent values for /, depending upon the structure of the molecule.
An excellent monograph, including a review of former work
on this subject and a complete bibliography, has recently been
published by Cheneveau.| ) |
At the present time, but few data are available for the
application of these formule to silicate glasses and to minerals
of simple, known composition. The present investigation was
undertaken to secure such data and to test the application of
the formule to several different silicate glasses and corre-
sponding minerals. The two series selected for study were the
soda-lime feldspar series and the three component system
CaO—MgO-Si0,, with especial emphasis on the metasilicates.
The glasses were prepared by mixing the pure components
and melting, then grinding and remelting several times to
secure homogeneity. The probable error in composition |
should not exceed 0°3 per cent.4{ Glasses rich in CaO and MgO
could not be prepared on account of their strong tendency to
crystallize. The crystals were prepared in the course of the
* Wied. Ann., xi, 70, 1880. + Zeitschr. f. phys. Chem., vii, 1, 1891.
{ Pogg. Ann., cxvii, 358, 1862. § Zeitschr. f. phys. Chem., iii, 210, 1889.
| Ann. d. Chem. et Phys., xii, 145, 289, 1907.
“| Allen, E. T., and W. P. White, this Journal (4), xxvii, 2, 1909.
and Density of Some Crystallized Silicates. 265
synthetic work-of the Geophysical Laboratory and the method
of preparation and purity are discussed in publications to
which explicit reference will be made further on.
Hie
ie
Na
eee
Bae 7 ,
154 y AE
eee ee eee
See eee aaa eeeee
__ J See 2 ae ea ae
Ss aaee 2 ae
eee d 80
390
Rerractirve InpExX.
100
Albite Anorthite
The indices of refraction of the glasses were determined by
the method of minimum deviation and each was checked by two
separate wedges. The measurements were made on a Gold-
schmidt two-circle goniometer, using lithium, sodium and thal-
lium lights, and the angles checked to the nearest minute.
The measurements for the two wedges usually checked to
within 0-0004 and the probable error is +0:0003. The results
for the measurements of the feldspar glasses are given in
Table 1, and are plotted in fig. 1; those for the metasilicates
of calcium and magnesium in Table 2 and fig. 2; and those of
the other silicates of calcium and magnesium in Table
REFRACTIVE INDEX.
pos SL
me ASEH
EE EEEEESSONNE
266 ES. Larsen—felation between the Refractive Index
Fie. 2.
PNP EPEE Te
RSSREE EE
BRREEESEEEeS
S00SSSeeeeeee eS
eee
BREEEREES..
H-} pA AG"
RES ps
acces
0 To 20 30 AOM ns 60. 70 = 90 100
As shown in the columns headed N»,,—WNy,; the lispemne
varies continuously, within the limits of error, between the
end members in both series. The next column, headed
and Density of Some Crystallized Silicates. 267
N—N’
N
for any intermediate member exceeds the value computed on
the assumption that it is an additive function of the end
members. In the (Ca,Mg)SiO, series this excess is positive
and is well beyond the limits of error. The plot of figure 2
shows a curve which is sensibly straight throughout its central
part but which bends down rather sharply at both ends. The
data for the feldspar glass show a negative deviation as indi-
cated by the curves plotted in figure 1. These are also sensibly
straight throughout their central portion, but bend up at both
ends.*
The specific gravities of the glasses were determined on
owder of 100 mesh size in a pyenometer, with water or zylene
at 25° C.+ Separate determinations on material from the same
melt usually checked to 0:002, but the difference is somewhat
greater when the powders are from different melts. The values
for the specific gravities are given in Tables 1, 2 and 3 in
the columns headed D and are plotted in figs. 3 and 4. The
values for the feldspar glasses were taken from the data of
Day and Allen.{ In the column headed
.100, gives the percentage which the index of refraction
100 is given
the percentage of deviation of the specific volume from the
TABLE I.
= | +2 ® epee =
g8| 3 | N N N e a D a
ae x | AN Li Na Th | a i 1 S
ie = 100-00 0-00 1-4864 |1-4891 1-4916 -0052 0-60 2-882/-4198 0-00
1°4865 /1°4889 (1:°4917 | 0052)
|
AbzAn,__| 65°37) 34:63 1°51386 |1°5168 |1:5194 |-0058/—0-16 2°483)-4027| +0-02
(1°5184 |1°5164 |1:5191 | ‘0057
Ab, An,_.| 48°55, 51°45 1°5281 |1°5309 |1°5335— -0054' 0°18 2°533 -3948) +. 0-11
| 1°5276 [15806 9 (1°5334 | 0058) |
Ab;Anz__| 32-05 67-95 1°5420+|1-5451—|1-5480 | -0060 —0-16 2-591 -3859| 0-07
| 1°0420 |1°5453 | 1:°5482—) 0062
Ab:An;. | 15°87) 84:13.1:5562 |1:5600 1-5628 -0066 —0-12 2-648)-3776|—0-15
1°5565 /1°5600 1°5629— | -0064)
| | |
a1 es ee 0°00'100°001°5720 = |1°5756 11-5786 |-0066, 0-00.2-700|-3704| 0-00
| 15718 |1°5754 [15786 |-0068'
* For data on similar deviations for isomorphous artificial crystals, see
Fock, Zeitschr. f. Kryst., iv, 583, 1880.
+ Isomorphism and thermal properties of the feldspars, Pub. No. 31, Car-
negie Institution of Washington, p. 55.
t Loe. cit.
268 LE. S. Larsen—Lelation between the Refractive Index
TABLE II.
a > S
Se ties bale = =
SO ro Za, Mes SHER
Bed) a) | Niu Nna Nm | Z, D > - ES |
ss & a le [ i
ale = Ai tint HIA} &
100:00 | 0:00 |1°6242 + !1-6281—/|1:6317 | -0075 2°904| -8444] 0-00
1°6240+ |1°6280 |1°63817 | -0077| 0:00 | 2°904).
95:00 | 5:00 |1°6224+4/1-6263 +|1:6300 | -0076) +.0-04 | 2-899] 3450) —0-09
(1°6221 = |1°6260+4 |1°6299 | -0078
85°26 | 14°74 |1°6183 |1°6222 |1:6256 | -0073)+0-09 | 2°892) -3458} —0-34
1°6187 /|1°6225 |1°6260 | -0078 2°891
74-00 | 26°00 1°6185 |1-6175 |1:6210 | -0075)+0-13 2°882) °3471; —0°57
1°6136 §1°6174 |1°6210 | -0074 2°880
64:00 | 36°00 |1°6084 (1°6122—/1°6155 +) -0071| +0-09 | 2:872| -3482) —0-80
'1°6084 + |1°6122 +|1°6156 +) -0072 2°873)
2°870
60°00 | 40°00 |1:6068 |1°6106 |1°6140 | :0072)+0-11 | 2°858) -8499| —0°51
1:6067 |1°6104 |1°6139 | -0072)
03°64 | 46°36 |1°6088 |1°6074 |1°6111 | :0073 +0-10 | 2°854| -3504) —0-71
1:6085 /1°6072 |1:6107 | -0072| 2°854
40°00 | 60:00 |1°5970 |1:6006—/|1-6035 +} -0065 +0-09 | 2°835) 8528] —0-73
1:0971 (1°6008+/1°6040 | -0069 2°834
30°00 | 70:00 1°5926—|1°5963 + |1°5994 | 0068) +0-09 | 2:819) -3545| —0°76
1°5921 (1:5957 |1°5990 | -0069 2823)
2°820
1°5819 |1:5856—|1:5887 | -0068)/+0-08 | 2°881) -3599| —0°28
1°5818 |1°5854 |1°5887 | :0069 2°877|
10°00*, 90:00*; 2879
11°5816 1°5851 15883 | 0067 2°880
15814 /1°5850 |1:5880 | -0066 2°879
5:00 | 95:00 |1°5787+4 |1:°5820+/1°5854 | -6067/—0:01 | 2°777) -3601| —0°45
1:5789 §1°5823 (1:5854 | -0065) aan TE :
0:00 |100°00 |1:°5768 |1°5802 |1:°5835 | -0067|) 0:00 | 2:758) -3627) 0:00
1°5766 |1°5800 |1°5831 | -0065 2-707
* These two determinations were made on glasses from separate melts.
additive value. For the (Ca,Mg)SiO, series the values are
negative and show clearly a contraction on mixing. The data
for the feldspar glasses are not consistent.
The data for the refractive index and density of the various
crystalline forms were taken from measurements made in the
Geophysical Laboratory on pure artificial material. The prob-
able error of the index of refraction is about + 0-002, while
that for the density is avout + 0°005. The indices of refraction
of quartz and of the feldspars are those of the natural minerals.
Sproiric GRAVITY.
i)
and Density of Some Crystallized Silicates.
TABLE ITI.
a x 2 D E @ ‘a
ae ° S > ba Nii Nna Nrn D
BOD xO a= 2
a _ =_ | Z
100-00 0-00 0:00 14°4567 | 14589 | 1-4612 0045 | 2-218
1°4565 1°4592. | 1°4612 0047
46°50 50°00 3°00 =: 1°6365 1°6405 1°6446 0081 2-954
1°6375 1°6416 1°6453 ‘0078 2-992
45°00 40-00 15°00 | 1°6349 | 1°6391 1°6427 “0078 2-966
1°6352 1°6393 1°6450 ‘0078 2°969
50-20 | 24:80} 25°00 | 1°6182 1°6224 1°6262 ‘0080 2°920
| 1°6185 1°6226 1°6259 ‘0074 2°921
Fie. 3.
_ eae ee eee
Jee eS ae eee aa
ees Ree ee or
_ US SaaS haar aans
{ase eee ese
eee A744
es
Albite
10
iSraosadtandiaeet
Bee ry
Slate thite
In birefracting minerals the mean index of Rue a oon was
taken
| {eam
2w+e
_ atbt+y
et 3
-100
270 =H. S. Larsen—Lelation between the Refractive Index
The specific refractivity of the various glasses and erystals
studied have been computed according to both the formula of
Gladstone and Dale and that of Lorentz and Lorenz, and the
results are tabulated in Tables 4,5 and 6. Table 4 gives the
data for the feldspar series. The third column gives the value
TABLE IV.
S S
ee Sy Seal Si
| a ) p = r sh il =| r La : ="
Nea) Poy tl |) Ba |e le i | a
lila Bee Clete ee Be a
| A MS | M A \G Ms hs
Glass | |
Bo aetons 1°4890 + |2°382 20538 = |-2058 0-00) 12117/-12117) 0-00
Ab,An,-__/1°5166 |2°483 -2081—|:2080—) + 0°05 12176) 12161] +0°12
Ab, An,-__/|1°5307 + |2°533 -2095 = =|-2094 |+0°05 12208) 12185] + 0°19
Ab, Ang-.-/1°5452 |2°591/°2104 =|:2105 |—0-08 "12206)-12206| 0-00
Ab, Ans_--|1°5600 |2°648)°2115 |-2119 |—0:19 12211) -12228/—0:14
Ang ree 1°5755 = /2°'700) -2182—|-2182—| 0:00 12248) 12248) 0:00
Feldspaz
Cae Ot 1°584 = (2605-2050 =| -2050 0:00 + 0°15)-11933)|-11933| 0-00) + 1:52
Ab,An,___|1'549 = 2°660 -2064 =|.2075 |—0-55) + 0°82/-11958)-12010| —0°43) + 1°82
Ab, An,-_.-/1°558 = 2°679 -2083 |:2088 =| —0°25) + 0°58) -12034|-12047/—0°11| +1°45
Ab, An,--_|1°568 (2°710 2096 |-2100 | |—0°20) + 0°88) 12073) 12083) 0-08] +1°10
Ab,Ans_._]1:577 = /2°738)°2111 |:2112 |—0-05) + 0-19|-12125)-12119| + 0-05) + 0°71
NG apa He 1°587 = (2°765) 221238 |-2128 0:00; + 0°40/°12154|°12154| 0:00|/+ 0°77
of K, as computed from the simpler formula, the next column
the value of K’, from the end members of the series, on the
assumption that it 1s an additive function.
ee
K
1
The column headed
.100 gives the percentage by which K, differs from the
This difference is within the limits
computed additive value.
of error for the glasses but is a little greater than the probable
error for the feldspars.
K —K"
The column headed —*~—— .100 gives the percentage by
K
which the specitic refractivity of a erystal differs from that of
a glass of the same composition. For the feldspars and their
glasses this difference is always positive and is somewhat
greater than the probable error.
In the last four columns of the same table, corresponding
values computed from the m’ formula are given. The deviation
from the additive relation is within the limits of error for
both the glass and the crystalline series as in the former case,
but the percentage of difference between the constant for a
Sprciric GRAVITY.
and Density of Some Crystallized Silicates. 271
glass and that for the feldspar of the same composition is
considerably greater for this formula and is well beyond the
probable error.
Table 5 gives the corresponding values for the calcium-
magnesium metasilicate series. Here also the law of mixtures
[2ne ae
BSCE
Seesen seessuuuaenae
va 90
pee tes ey
Beers sea IN
__ eee ee eee ees
CaSiOs MeSiO;
holds within the limits of error for the glasses, but when the
constant for a glass is compared with that of the crystal ot the
same composition, the percentage of difference is as great as
3°2 per cent if computed from the simple formula, and 5°3 per
cent 1f computed from the n* formula. In this series the
constant for the glasses is always greater than that for the
erystalline material.
The results for the CaO-MgO-Si0, series are listed in Table
6. They accord well with the former results in that both
constants are additive for mixtures of the glasses while neither
agree when minerals are compared with classes or with each
other. The percentage difference between the value of K, for
a glass and that of K’, for a crystalline material of the same
composition may be either positive or negative, and become as
Index
tVE
between the Refract
zon
Lt. S. Larsen— Relat
272
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273
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L Sil
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and Density of Some Crystall
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274 EF. S. Larsen—Lelation between the Refractive Index, ete.
great as —11 percent, asin CaO. The percentage of differ-
ence for the 2° formula may likewise be positive or negative
and reaches a value of 9°8 per cent for CaO.
Summary.
A study of the refractive indices and densities of silicate
glasses and of artificial minerals was made to test the formulae
of Gladstone and Dale and of Lorentz and Lorenz. Neither
the refractive indices nor the specific volumes of the glasses
are strictly additive functions, but there may be an increase or
a decrease of volume and a corresponding decrease or increase
of the refractive index. The specific refractivity computed
from either formula is sensibly additive for the glasses and
nearly so for the isomorphous series of soda-lime feldspars,
but when crystals are compared with glasses of the same
composition, or with other crystals, the values of the specific
refractivity, computed from either formula, nay differ by as
much as eleven per cent. They are usually higher for the
glasses. One formula appears to hold as well as the other, but
the formula of Gladstone and Dale has the advantage of
simplicity.
Geophysical Laboratory,
Carnegie Institution of Washington,
Washington, D. C., May, 1909.
. ff
B. Smith—Note on the Miocene Drum Fish. O75
Art. XXIX.—Wote on the Miocene Drum Fish—Pogonias
multidentatus Cope; by Bournetr Smiru.
Introduction.
Tuts rare species of the Virginia Miocene was originally
described by Cope in 1869* and in 1908 the type was figured
the first time by Hussakoft in the catalogue of fossil fishes
published by the American Museum of Natural History. As
far as the writer can learn, the type specimen has remained,
for nearly forty years, the only known example of the species
and it has always been regarded as a “left superior
pharyngeal.”
Another specimen of a pharyngeal plate obviously referable
to Pogonias was recently collected by the writer from the
Miocene of Maryland. It is apparently identical with Cope’s
species though the pattern of the bean-like crushing teeth
differs slightly from that of the type. The chiet points of
interest attaching to this second specimen are the following:
(1) it gives us slight but much needed information as to the
range ‘and distribution of the fossil Drums, and (2) it furnishes
additional data for working out one or two points in the
structure of the phary1 ngeals whick up to now have remained
obscure. Taking up the second of these considerations, we
find that, strangely enough, the type has always been
interpreted as a “left superior pharyngeal.” It is indeed a
part of the upper pharyngeal crushing pavement, but instead
of being situated on the left side it was on the right side and
furthermore represents only one of the three well-defined
pharyngo-branchial plates which occur on either side in the
pharynx of Pogonias.
ae ison of the Pharyngeal Teeth of Pogonias, Cynoscion,
and Micropogon.
In order to understand the osteological value of the known
parts of the fossil Pogonias multidentatus it is necessary to
review briefly the conditions met with in the branchial arches
of some of the recent Scizenidae. In this family we find that
the different genera manifest a great variety in the form and
structure of the pharyngeal teeth. In some the pharyngeal
plates are set with simple sharp denticles; others have in place
of denticles blunt bean-like crushing elements, while between
these two extremes we find forms whose pharyngeals are
* Cope, E. D., Proc. Bost. Soc. Nat. Hist., xii, p. 310.
+ Hussakof, L., Bull. Am. Mus. Nat. Hist., vol. xxv.
276 B. Smith— Note on the Miocene Drum Fish.
adapted for either cutting or crushing. The most casual study
of such a series suggests that the crushing type has resulted
from a modification of the plate, which is covered with
denticles. For this reason it is advisable to consider the
pharyngeals of some scizenoid genus which is primitive in this
respect (Cynoscion) and compare them with those of a less
primitive form (J/zeropogon), and finally with those of a highly
specialized form (Pogonzas). The species which have been
selected for this purpose are Cynoscion nebulosus (C, and V.),
Micropogon undulatus (L.) and Pogonias cromis (I).
The Lower Pharyngeal Plates.—In Cynoscion nebulosus
the lower pharyngeals differ little from those of the normal
teleost fish. They represent the inward plate-like expansions
from the rudimentary fifth cerato-branchial, are not fused but
remain distinct (right and left), and are covered by sharp
backwardly curved denticles which are largest along the inner
(median) anterior margin of each plate. In Jscropogon
undulatus the same general shape prevails but each plate is
proportionately broader and heavier. When, however, the
dental elements of the plates are examined we find a marked
change from the condition observed in Cynoscion, for in
Micrepogon the. denticles are much fewer, and though still
small and sharp on the lateral (outside) and postero-lateral
regions they have become large and blunted on the anterior —
Inner (median) border. If now we extend our comparison to
Pogonias cromis we find that the inwardly directed plate-
like portion of each fifth cerato-branchial has expanded until
it meets its fellow on the opposite side and is firmly united by
suture with it. In addition each bone has developed on its
under surface a prominent process directed downward, for-
ward, and outward for the attachment of the powerful muscles
needed in the operation of the fused plates. In conjunction
with this fusion and strengthening the functional surface has
developed bean-like crushing teeth. These are largest along
the median (inner) margin of each one of the plates and
decrease in size forward, backward, and outward. A few
sharp denticles are still retained on the postero-lateral margins
of each member, but the transition from sharp denticles to
crushing elements can only be well seen in young examples
of the species (fig. 3).
The Upper Pharyngeal Plates—The upper pharyngeal
plates of Cynoscion nebulosus exhibit no marked divergence
from the normal teleost type. There are three well-marked upper
plates on each side all covered with sharp backwardly curved
denticles. The anterior plates (right and left) are narrow,
he forward and outside of the second pair of plates, and are
directed forward and inward. The second pair of plates are
B. Smith—Note on the Miocene Drum Fish. OT
the largest of the three and the denticles which they bear on
their inner margins excel in size those of either the first or
third pair. The posterior pair of plates are larger than the
anterior pair but the denticles on their inner margins are very
weak.
In Micropogon undulatus the plates of the second pair have
increased in size at the expense of those of the first and third
pairs. It is true the third (posterior) pair are not greatly
reduced but their surfaces are covered with but small and
weak denticles. The plates of the first (anterior) pair are
much reduced in size and covered with weak denticles. ‘The
plates of the second pair are large, the outer (lateral) margins
bear fairly sharp denticles while the inner (median) and cen-
tral regions carry denticles which are larger and more blunt.
Turning now to the superior pharyngeals of Pogonias
cromis, we find that the second pair of plates is proportionately
much larger j in size, while on the other hand the first and third
plates are proportionately much smaller, being in each case
narrow crescentic elements which are closely applied to the
curved anterior and posterior margins of each plate in the
second pair. These plates of the first and third pairs carry
weak degenerate denticles. In P. cromis it is the second pair
of plates which command our attention, for these are abnor-
mally large in size and the denticles have for the most part
been changed into blunt crushing elements. These bean-like
teeth are largest along the inner margin of each plate midway
between its anterior and posterior ends. From this region
(on each plate) the teeth become smaller as we pass forward,
backward, and outward. In addition as we go outward the
typical bean-like condition is less and less marked, the teeth
becoming gradually less and less blunt until we reach a small
patch on the extreme outer margin which still retains the
primitive sharp denticles. As might be expected, this transi-
tion between denticles on the one hand and crushing teeth on
the other is much more evident in the plates of young individ-
uals of Pogonias cromis ; for the old examples of the species
have but a relatively small denticled area and only a few
transitional teeth (figs. 7 and 8).
Comparison of the Pharyngeal Teeth of Pogonias cromis and
Pogonias multidentatus.
As stated above, the Miocene Pogonias multedentatus Cope
is known by but two specimens. The type is a right superior
pharyngeal from Nomini Cliffs, Westmoreland County,
Virginia, and the other specimen is a left superior from the
St. Mary’s Formation of St. Mary’s River, Maryland. Though
Am. Jour. Sc1.—Fourta Series, Vout. XXVIII, No. 165.—Srnpremper, 1909.
19
278 B. Snith— Note on the Miocene Drum Fish.
the fossils are fr agmentary, there can be no question as to their
osteological value “when we compare them with the correspond-
ing parts which have been taken from the branchial arches of
the recent P. eromis (L.).
Considering first the type of Pogonias 1 m in we
see that the bean-like crushing elements have all disappeared
leaving only their sockets, while the plate itself has lost much
of its outer and posterior portions. Some of the anterior part
is likewise gone. On its dorsal surface the most striking points
observed are (1) the ridge on the anterior central portion of
the plate leading backward to the knob, which in the recent
Drum serves for the attachment of the second epibranchial ;
(2) a portion of the large rounded knob at its posterior extrem-
ity, which in the hving form furnishes the surface for the
attachment of the broadly expanded proximal end of the
fourth epibranchial ; and (3) the strcng ridge and process on the
median margin, which is for muscular attachment. These
three features are unmistakable and can all be checked with
similar ones in the corresponding plate of P. cromes. _ Espe-
cially is this true for the large posterior knob, whose surface
bears the same minute wavy ~ ridges which are found in the
living form.
When, now, we examine the dorsal surface of the Maryland
fossil, we find, in spite of its fragmentary condition, that it
agrees in every structural feature with the second left superior
pharyngeal plate of P. cromzs, and that there can be no ques-
tion of the position which it oceupied in the pharynx. The
broken surface along the inner margin shows that the dorsally
directed ridge was here well developed. The ridge which led
to the knob for the second epibranchial attachment is unusually
sharp and strong, much more so than in the type, and in this
respect it closely approaches the condition observed in im-
mature examples of the recent P. cromis.
Range and Probable Evolution of Pogonias.
In Dr. Hay’s “Bibliography and Catalogue of the Fossil
Vertebrata 2 North America® two species of Pogontas are
listed. The first of. these, P. cromis, is mentioned by Leidy7,
as being found in the sands of the Ashley River, South
Carolina; the second, P. multidentatus, was described by Cope
as having come from the Miocene Cliffs of Nomini, Westmore-
land County, Virginia. Inasmuch as the Calv ert, Choptank,
and St. Mary’s strata are all extensively exposed at this local-
invades 1611S unfor tunately impossible to tell from Cope’s deserip-
A Bull, WS. Gos. Now 719) Washinetons 90.
+ Indications of Twelve Species of Fossil Fishes, Proc. Acad. Nat. Sci.,
Phila., vii, pp. 3895-97.
+t Md. Geol. Surv. Miocene, pp. 1xxix and lxxx.
B. Smith—-Note on the Miocene Drum Fish. 279
tion just which one of these Miocene horizons furnished the
fossil. It is probable, however, that the type came from the
St. Mary’s formation, for this is the one in which the species
has been found in Maryland.
The very meager fossil material* at the writer’s disposal is
hardly sufticient to illustrate any evolutional changes which
may have taken place in the genus during its geological range.
It is, therefore, to be regretted that we have, as yet, no means
of checking the probable phylogeny which is suggested by an
ontogenetic series of the pharyngeals of the recent P. cromis.
It is evident from such a series that this peculiar type of crush-
ing apparatus was developed by (1) the enlargement of the
second pair of upper plates, (2) a progressive change from the
inner margins outward from denticles to crushing teeth in both
upper and lower plates, and (3) the fusion of the two lower
plates. The enlargement of the second pair of upper pharyn-
geals was accompanied by a corresponding reduction of the
first and third cies together with a degeneration of their
denticles. In both the second pair of upper plates and in the
fused lower plates the young examples of this species exhibit
every gradation between sharp denticle and blunt crushing
tooth (figs. 3, 7). In the young the denticled area is relatively
quite large, while in the old individuals a few blunt denticles
only are found on the outer margins of the upper and os the
postero-lateral angles of the lower fused plates (figs. 4,
In conclusion, we can say that the peculiar Pee
apparatus in the pharynx of Pogonias is, in all probability, the
product of a series of evolutional changes which in a general
way corresponded to those shown in the ontogeny of P. cromis,
and it is also reasonable to suppose that the Pogonias stock,
which had acquired its generic characters as far back as the
Miocene, was preceded in time by forms the pharyngeals of
which had reached a stage of specialization somewhat “similar
to that exhibited by JJicropogon undulatus. Though
recognizing fully the scantiness of the data, it is believed that
the mor phological gradations exhibited by the lower pharyn-
ar of Cynoscion, Micropogon, and Pogonias (P1. ; figs.
1, 2, 3, 4), and by the upper pharyngeals (PI. I, figs. 5, 6, 7, 8)
of the same three genera. represent an approximation o the
phylogenetic changes which have culminated in the crush-
ing apparatus of Pogonias.
‘Acknowledgments are due to Prof. Bashford Dean of the
American Museum of Natural Histor y tor the loan of type
material and to Mrs. Ethel Ostrander Smith for the careful
execution of the drawings here reproduced.
*JI have not yet been able to locate Leidy’s specimens from the Ashley
River Sands.
280 B. Smith— Note on the Miocene Drum Fish.
Fies. 1-9.
B. Sinith— Note on the Miocene Drum Fish. 981
EXPLANATION OF FIGURES 1-9.
Fic. 1.—Cynoscion nebulosus (C. and V.). Lower pharyngeals (functional
surface). Length along outer margin=42™™, Plates covered with
sharp denticles.
Fie. 2.—Micropogon undulatus (L.). Lower pharyngeals (functional sur-
face). Length along outer margin= 24™™, Plates relatively broade!
than in fig. 1, and with large blunt denticles on the inner margin of each
plate.
Fic. 3.—Pogonias cromis (L.). Lower pharyngeals (functional surface) of
young individual. Length along outer margin =38"™™. Plate fused.
crushing teeth developed in the central region, but many sharp denti-
cles still retained on the postero-lateral angles.
Fic. 4—Pogonias cromis (L). Lower pharyngeals (functional surface) of
mature individual. Length along outer margin =108™™. An advance
on the condition shown in fig. 3. Denticles replaced by crushing teeth,
though these are sharper on the postero-lateral angles.
Fig. o—Cynoscion nebulosus (C. and V.). Left upper pharyngeals (func-
tional surface). Length = 28™™. All three plates covered with sharp
denticles.
Fie. 6.—Micropogon undulatus (L). Left upper pharyngeals (functional
surface). Length=17°3™™. Second plate proportionately larger than
in fig. 0, its denticles larger and more blunt on the inner margin.
Fic. %.—Pogonias cromis (L.). Left upper pharyngeals (functional ser-
face) of young individual. Length =32™™. Second plate proportion-
ately very large with crushing teeth developed on its inner margin, but
with many sharp denticles still retained on its outer margin.
Fic. 8.—Pogonias cromis (L.). Second left upper pharyngeals (functional
surface) of mature individual. Length =83™™. An advance on the
condition shown in fig. 7, the crushing teeth occupying nearly the
entire plate with but a few denticles on the outer margin.
Fic. 9—Pogonias cromis (L.). Second left upper pharyngeal (dorsal sur-
face) of immature individual showing the processes for the attachment
of the epibranchials. The fourth arch attaches to the large rounded
knob on the posterior margin, the third just forward and to the left,
and the second arch is attached to the process shown in the forward
central region of the plate. The process on the right is for muscular
attachment. Length = 42™™,
All the figures are arranged with the anterior end uppermost.
982 B. Snith— Note on the Miocene Drum Fish.
lnné, 0),
Fie. 10.—Pogonius multidentatus Cope. Type, Nomini Cliffs, Westmore -
land County, Virginia. Second right upper pharyngeal (functional
surface) with crushing teeth gone. Length = 49"™,
Fic. 11.—P. multidentatus Cope. St. Mary’s Formation, St. Mary’s River,
Maryland. Second left upper pharyngeal (functional surface) with
crushing teeth gone. One successional tooth shows on the posterior
part of the inner margin. Length = 35".
‘Fig. 12. Fic. 13.
Fic. 12.—Dorsal surface of fig. 11 showing ridge leading to the second
epibranchial attachment.
Fic. 13.—Dorsal surface of fig. 10, showing the large rounded knob on the
posterio-lateral region which served for the attachment of the fourth
epibranchial.
Figures all arranged with the anterior end uppermost.
T. D. A. Cockerell— Description of Tertiary Insects. 288
Art. XXX.—Description of Tertiary Insects, VIL; by
TD. A. CockERELt:
ORTUOPTERA.
Teniopodites gen. nov. (Orthoptera ; Acridiine).
Tremrina long and comparatively narrow ; the inferior (anai)
field reduced basally ; the costa rather full, arching near the
base as in modern TZteniopodu; subcostal nervure closely
appressed to radial, branching before the middle of the tegen,
the two branches running parallel and extremely close together:
radius also with two parallel branches running very close
together. Spots round and very distinct, much as in 1 Teniopoda.
Although the spotting of the tegmen is very well preserved,
most of the venation is obscure. The question may be raised
whether there was not a vein (first subcostal) traversing the
costal field as in living Zwnzopoda, but not now visible. Tow-
ever, this vein (cf. T. var ypennis RKehn, Proc. Acad. Nai. Sci.
Phila. | 1005, p.405, f. 11) separates the spots of the costal
field into two series, one above and one below; in the fossil no
such separation is visible, and it is impossible to draw a line
which could represent the vein, without passing through some
of the spots. The radius is more like that of ordinary Acrid-
ians than Zwniopoda.
Teniopodites pardalis sp. nov. Figure 1.
Tegmen about 32™ long, width 5™™ about 6™™ from base,
8™" about 25" from base ; spots as preserved reddish-brown,
very distinct, half to 1™™ broad ; about 18 spots in costal field ;
apex of costal arch about 33™" from base of tegmen. No
other parts preserved.
fab.—F lorissant, Colorado, in the Miocene shales, Station
13 B (1908). - The ‘plant Sabina linguefolia is on the same
slab, nearly touching the tegmen. A photograph of the fossil
was submitted to Mr. A. N. Caudell, who noted a resemblance
to the spotted-winged species of Zropidacris, and also to the
genera Zoniopoda and Diponthus. To me the tegmen seems
exceedingly like that of Zeniopoda (a Mexican genus which
enters the United States in southern New Mexico), and I
believe there is really close affinity. A new generic name is
proposed, because the venation is distinctive, and it is impossible
to definitely refer the insect to any modern genus without a
knowledge of the thoracic and other characters. In the macula-
tion, and in the closely appressed veins, 7w@niopodites presents
a rather strong superticial resemblance to the Australian
284 T. D. A. Cockerell— Description of a Insects.
Tettigoniid genus Aphippithyta, although in ae genus, so
far as known to me, there are no spots in the costal field.
Tees, Je.
Teeniopodites pardalis.
Gryllacris mutilata sp. nov. Figure 2.
@. Length, exclusive of ovipositor, 833""; with ovipositor
about 40; ovipositor strongly curved, its length along the
GUIAVE slightly over 10: length of head from vertex to apex
of mandibles about 6™" ; length of prothorax 43"™. Tegomina
and wings ample, the tegmina incomplete, but length about
38°"; their markings consisting of fine transverse more or
less broken reddish-brown bands producing a mottled effect;
venation not well preserved, but essentially as in Gryllacris,
the costal and subcostal veins each with strong oblique upper
branches, the subcostal connected with the radius by straight
transverse veins, the radius with strong oblique branches
below.
Gryllacris mutilata Ckll.
A. Marking of tegmen. B. Ovipositor.
[Tab.—Mhiocene shales at Florissant, Colorado, 1908 (Geo. V
ftohwer). This is considerably larger than G. cinerzs Seudder.
from Florissant, and is readily distineuished by the markings of
the tegmina. Scudder remarks that @. cine? 7s, as well as s the
European Tertiary species of Gryllacris, belong to the genus
in a broad sense, and tlus is equally true oe G. Na It is
more than likely that if these insects were perfectly preserved
they could some of them be made the types of new genera; but
T. D. A. Cockerell— Description of Tertiary Insects. 285
it must be added that modern Gryllacris includes a great mul-
titude (over 170) of species, having various diverse characters,
and spread over the Neotropical, Australian, Oriental, and
Ethiopian regions. The venation of some of these (e.g. G.
tibialis Sery., G. signifera Stoll, G. larvata Reln) is strik-
ingly diverse, but is probably very variable within specific
limits.
Paleorehnia maculata Ckll. Figure 3.
Florissant, in the Miocene shales. This species was described
in Entomological News, 1908, p. 126, but although a figure was
HinGereys
Paleorehnia maculata Ckll.
sent to the editor it was not published. A figure of the type
specimen, showing the very characteristic markings, is accord-
ingly now offered. |
Diprera.
Tipula (?) hepialina sp. nov.
Pupa slightly over 21™™ long, nearly uniformly cylindrical,
breadth in middle 5™"; wing sheaths short, their tips about
7™™ from the cephalic end.
I had at first supposed this pupa to be lepidopterous, closely
related to Hepialus. On examining it with a microscope, the
compound eyes of the imago could be seen partially preserved,
with many distinct facets, and these occupied a space appar-
ently too large for the eye of any Hepialid, but accorded very
well with the Tipulids. It was then noticed that the leg-
sheaths extended far beyond the wing-sheaths, quite as in the
286 7. D. A. Cockerell—Description of Tertiary Insects.
Tipulidee, but not at all resembling Hepialide. The extreme
brevity of the wing-sheaths also indicated a Tipulid, although
the characteristic respiratory processes were not preserved.
The pupa of Dicranota has five pairs of ventral psendopods or
tubercles (ci. Miall, Trans. Ent. Soe. Lond., 1893, pl. xiii); the
fossil pupa has the ‘three posterior pairs well represented, ‘only
between them is a third, so that each segment has a little row
of three closely adjacent tubercles. There are very distinct
lines marking the middle segments, as in the pupa of Zipula
jfiavicans (cf. Needham, Bull. 68, New York State Museum,
ple s10)):
[RG aby
Tipula hepialina Ckll.
fHlab.— Miocene shales of Florissant, Colorado, Sta. 23
(W. P. Cockerell, 1908).
Tipula sp. nov.
A specimen in the Museum of Yale University, collected at
Florissant (Miocene shales) by Mrs. ©. Hill, is remarkable for
the length of the legs. The venation cannot be made out, so
it is hardly practicable to name the species. The specimen, a
male, oe as follows in mm.: |
Wing | ay body about 15; middle femur 10; middle tibia
+ tarsus 262; hind leg 44.
Tipula dlauda Scudd., with wings about the same size, has
the hind legs distinctly shorter : the combined femora, tibiee
and tarsi (ineasurements given separately by Scudder) meas-
MCI Bi ay SN OMe On “the Scudderian species show such
measurements as ours, which is Dee new.
Mr. D. W. Doane kindly examined the legs of the living
species of Zipula, and found that some have them fully as
long. Thus he found Zipula infuscata § to measure as
follows inmm.: wing 16; body 16; middle femur 13; middle
tibia + tarsus 30 ; hind leo D6.
Bosworth—Iodometric Determination of Silver. 287
Arr. XXXI.—A Method for the Lodometric Determination
of Silver Based upon the Reducing Action of Potassium
Arsenite; by Rowiann S. Bosworrn.
[Contributions from the Kent Chemical Laboratory of Yale Univ.—ccii. ]
Ir is well known that an ammoniacal solution of silver
arsenite deposits metallic silver when the ammonia is evap-
orated by boiling. During this reaction, by which the silver
salt 1s reduced, “he arsenious acid become oxidized to the
higher onion of oxidation, where arsenic has a valence of
tive, according to the equation
29Ag,0+ As,0,= As,0,+4Ag.
The present paper deals with some work done with the purpose
of determining whether this reaction was quantitative and of
devising a rapid iodometric method for the determination of
silver based upon the reduction of the silver salt to the metal.
Experiments were first performed upon a silver nitrate solu-
tion of known strength according to the following plan: To
a definite portion of a standard ‘solution of silver nitrate was
added a known volume of a standard potassium arsenite
solution in excess of the amount necessary to reduce the silver
salt present. Ammonia was then added in suflicient quantity
to dissolve the precipitate formed, and the resulting solution
was diluted to 100° and boiled until the escaping vapor gave
no test for free ammonia with moistened litmus paper. The
solution, out of which metallic silver had then separated, was
filtered, cooled, and made faintly acid in order to neutralize
any possible trace of ammonia which might remain. After
making alkaline with sodium bicarbonate, the excess of potas-
sium arsenite was titrated with N/10 iodine. The silver value
of the iodine used was subtracted from that of the potassium
arsenite originally taken, and the result used as a measure of
the silver present. In Table I, A, are given the results of
experiments performed in the manner described above.
The effect was next tried of the use of sodium bicarbonate
as a means for producing alkalinity in place of the ammonia.
The following procedure was used: To a solution of silver
nitrate was added an excess of standard potassium arsenite
solution. The mixture was made alkaline by means of 25°
of a saturated solution of sodium bicarbonate, diluted to 100%,
and boiled until the precipitate of silver arsenite was converted
to metallic silver. The solution was then filtered and aciditied,
in order to break up the neutral carbonate formed by boiling
the bicarbonate. Finally the solution was made alkaline with
sodium bicarbonate and the potassium arsenite present was
288 Bosworth—Tlodometric Determination of Silver.
titrated with N/10 iodine, the titration giving a measure of the
silver originally taken. The details of these experiments are
given in Table I, B.
TasBie I.
KH.AsO; added I, used
— PSS) — ~—— Error
Silver Silver Silver Silver in terms of
taken value value found silver
erm. enn”. orm. oma, erm. germ. germ.
A
Use of NH,OH with filtering
0°1054 20 0°2000 8°53 0°:0949 0°'1051 —0:0003
0°1054 20 0°2000 8:52 0:0948 0°1052 —(0°0002
0:'1054 30 0°3000 17°42 0:1939 0°1061 +0:0007
0°1159 20 0°2000 760 0°0846 0°1154 -—0°0005
0°1054 Dali 0'2100 Bi Oo Oss} 0°1057 + 0°0008
0:1054 20 0°2000 8°48 0°0944 0°1056 + 0°:0002
B
Use of NaHCO; with filtering
0°1054 15 O'1618 HS OOS 7 Il 0°:1047 — 0'0007
0°1054 23 Q°248] Wabi 4e | Oelas@ 0°'1051 —0°0003
0°1054 YP 0°1295 2Z-A0 0:0 243 0°1052 —0:0002
0°1054 15 0O°1618 5°60 0°0566 0°1052 — 0°0002
O'1054 15 01618 5°05 = 0'0S61 0°1057 +0°0005
0°1054 20 0°2158 1091 O°1104 0'1054 + 0°0000
0°2635 By) 0°3776 11°33 0°1146 0°2630 —0°0005
Since the precipitate of metallic silver, in the experiments
of both A and B, was in a well coagulated condition, experi-
ments were carried on in which filtration was omitted, the
titration being made in the presence of the precipitate. The
results given in Table II, A and B, show that the precipitate
has no appreciable effect upon the titration. If nitric acid
were present in the solution of the silver salt, as is usually the
case in analysis, it would be converted to a nitrate by the
addition of the alkali. In order to prove that the presence of
a considerable amount of sodium nitrate would not hinder the
reduction of the silver salt, determinations were made after
the addition of two grams of that substance, with the uni-
formly good results shown in Table II, C.
Since in analysis it is often necessary to determine silver
when copper or lead or both are also present in solution, and
since silver can, with proper precautions, be separated from
either of these metals by precipitation with hydrochloric acid,
it seemed desirable to accomplish the reduction of silver when it
was in the form of the chloride. Consequently, determina-
Bosworth—Lodometric Determination of Silver. 289
TaBsieE IT.
KH,AsO; added I, used
— A = A —_ Error
Silver Silver Silver Silver in terms of
taken value value found silver
erm. em erm. em’. erm. erm. erm.
A
Use of NH,OH. Titration carried on in presence of the precipitate
0°1054 20 0°2000 8°55 0'0952 0°1048 —0°0V006
0°1054 20 0°2000 8°50 0°0946 0°1054 +0°0000
0°1054 23 0°2300 E28. 01256 0°1044 —0°0010
0°1054 20 0°2000 8°45 0°0941 0°1059 +0°0005
071054 20 6°2000 848 O0°'0944 0°1056 + 0°0002
B
Use of NaHCO 3. Titration carried on in presence of the precipitate
0°1054 18 0°1800 6°80 0:°0757 0°1045 SOUL
0°1054 | 0°1700 5°81 0:0647 0°1053 —0-°0001
0°1054 15 0°1500 4°00 0°0445 0°1055 +0:°0001
0°1054 21 0°2100 9°45 0°1052 0°1048 —0'0006
0°1054 25 0°2500 13°00 0°1447 0°1053 —0°0001
0°1054 31 0°3100 18°40 0°2048 0°1052 —0°0002
C
Use of NaHCO;. 2 germs. of NaNO; present. Titration carried on in
presence of precipitate
0°0949 ya 0°2100 10°42 +0°1160 0°0940 —0°0009
0:1054 21 0°2100 9°43 0°1050 0°1050 —0°0004
0°1265 20 0°2000 6°60 0°0735 0°1265 + 0°0000
0°1686 21 0°2100 3°80 0°0432 0°1678 —0°0008
0°1054 15 0°1500 4°08 0:°0454 0°1046 —0°0008
tions were made according to the following plan, the details of
the experiments being given in Table III], A. From a known
amount of a standard solution the silver was precipitated with
hydrochloric acid, and filtered upon asbestos. The precipitate
was then acted upon by strong ammonia, the mixture being
allowed to stand until the silver chloride was completely dis.
solved. The solution was diluted to 100° and reduction
accomplished by adding an excess of standard potassium
arsenite, and boiling the resulting solution. The excess of
potassium arsenite was subsequently titrated according to the
procedure outlined previously in this paper. In Table III, B,
are details of determinations similarly made, in which the
silver was separated from 0:09 grm. of copper. The experi-
ments in Table III, C, illustrate “the separation of silver from
0-2 grm. of lead, and in the experiment recorded in D the
silver was precipitated from a solution containing 0:09 erm. of
copper and 0-2 grm. of lead.
From the results recorded in this paper, it is evident that
silver can be easily and accurately estimated, either in solution
290 Bosworth—Lodometric Determination of Silver.
: Tassie III.
KH.AsO; added I; used Error
Silver — -A———_, — -—— Silver in terms of
taken Silver Silver found silver
erm. em. erm. em. erm. erm. erm.
A
Reduction of precipitated AgCl
O ONG 15 0°1619 5°40 0°0599 0°1020 + 0°0008
0°1017 15 O:1619 5°44 0:0603 0°1016 —0°0001
Oa Oae 15 0°1619 5°40 0°0599 0°1020 + 0°0003
0°1017 15 0°1619 d°42 0°0601 0°1018 + 0°0001
0°1017 rg 0°1854 744 0°0825 0°1009 —0-0008
B
Reduction of AgCl precipitated in the presence of 0°09 grm. of copper.
O2kOuiy 15 OG Ie 5°41 0°0600 0°1019 + 0°0002
0°1017 15 0°1619 5°44 0°0603 0'1016 —0°0001
0°1017 15 0°1619 5°39 0°0598 O:1021 + 0°0004
C
Reduction of AgCl precipitated in the presence of 0:2 grm. of lead
Oal2 20 16 0:1726 4.57 0°0507 OM ILZNLY) —0-0001
0°1108 15 OL Ol) 4°60 0°0510 O°1109 +0°0001
D
Reduction of AgCl precipitated from a solution containing 0:09 grm. of
copper and 0°2 grm. of lead
MOT 15 0°1619 5°45 0°0604 O-1015 —0'0002
or in the form of the precipitated chloride, by adding an excess
of standard potassium arsenite, boiling in alkaline solution to
accomplish the reduction of the silver salt to metallic silver,
and titrating the excess of potassium arsenite with iodine.
The silver value of the iodine used is to be subtracted from
that of the potassium arsenite originally taken, the result
giving the amount of silver present.
SIMON NEWCOMB.
Tus death of Simon Neweomb at his home in Washington
on July 12, 1909, after a long and painful illness, terminated a
life of extraordinary activity. His last contribution to his
theory of The Motion of the Moon was finished a few weeks
only before his death and was consciously hastened on account
of his knowledge of the speedy approach of the end.
Simon Newcomb was born in Wallace, Nova Scotia, March
12, 1835. His father, John Benton Newcomb, was of Amer-
ican desceat whose ancestors had settled in Canada in 1761.
Simon Newcomb. 291
He returned to the United States in 1852 and was followed in
the succeeding year by Simon Newcomb, who, like his father,
had been a teacher in Canada. For the next two years the
young Newcomb taught school in Maryland and, while thus
engaged, awakened the interest of Joseph Henry, the Secretary
of the Smithsonian Institution, by means of a mathematical
paper which was submitted to him. Henry secured for the
young teacher an appointment as a computer in the U.S.
Nautical Almanac, which was then published at Cambridge.
While here he became a student in the Lawrence Scientific
School, which completed his academic life until he returned to
it as a Professor of Mathematics and Astronomy at Johns
Hopkins University. This chair he held from 1884 until 1894.
While occupying the position of a computer in the Nautical
Almanae Office, Newcomb published a paper on the orbits of
a number of the asteroids which at once secured for him a
world-wide reputation as a master in this difficult field of
research and in which he was destined to lead his contem-
poraries. His exceptional merits were quickly recognized and
he was given, in 1861, an appointment as a professor of
mathematics in the U. S. Naval Academy with an assignment
to duty in the Naval Observatory. This title he held until
1877, when he became Senior Professor of Mathematics. He
retired in accordance with the law at the age of sixty-two, in
1897. During this period of twenty years Professor Newcomb
was Director of the American Ephemeris and Nautical
Almanae.
While connected with the Naval Observatory, Newcomb, in
pursuit of his favorite study, advanced observational science in
a remarkable degree. In order to secure better values of the
masses of Uranus and Neptune, essential to his great project
of perfecting the tables of the Solar System, it was necessary
to have more perfect observations of the satellites of these two
planets, and there were no telescopes in existence adequate to
this end. This prompted him to a careful study of the best
type of instrument for such observations, together with the
probable limitations of the contemporary optical art, finally
fixing upon a refractor of twenty-six inches aperture, for the
construction of which he obtained a grant from Congress.
This, the first of the great modern telescopes, was completed
in 1876 and was made famous in August of the following year
by the discovery of the two satellites of Mars by Professor
Asaph Hall. Meanwhile, Newcomb had observed the satellites
of the two most remote planets of our System and employed
his results in perfecting the tables for Uranus and Neptune,
which have been used by all astronomers from the moment of
their first appearance. The knowledge and experience acquired
2992, Semon Newcomb.
by Newcomb in his studies of telescopes made him an invalua-
ble adviser in the equipment of the Lick Observatory.
This grand project of Newcomb led to two other extensive
investigations which a man of less intellectual breadth and
courage might have been expected to leave to others. For a
long time there had been growing a doubt among astronomers
as to the accuracy of the accepted value of the fundamental
unit of the Solar System, namely, the true distance of the Sun
from the Earth. This value was established by Eneke from
observations of the transits of Venus. Newcomb undertook
the enormous labor of a complete rediscussion of this result
from all the original records of the observations of transits of
Venus previous to that of 1882, and, from a judicial weighing
of probabilities which has commanded admiration from all
competent critics, derived a value which was almost identical
with that now accepted.
An independent method of establishing the same constant is
derived by combining the observed aberration of light with its.
measured velocity. Professor Michelson, then an Ensign in
the Navy, had improved Foucault’s method of measuring the
velocity of light and, by a series of skillful experiments, had
added greatly to. the precision of our knowledge of its value.
Newcomb secured Michelson’s aid and a grant of money from
Congress to meet the expenses of a continuation of these
measures on the largest effective scale. The results of such
cooperation were most brilliant, and they attach the name of
the astronomer to the historical determinations of the great
constant of physical science as well to that of astronomy.
The world of science has not failed to recognize and reward,
as far as possible, the great services of Simon Newcomb. In
our own country hardly a university of prominence has with-
held from him its highest honors. The Institute of France
made him a correspondent in 1874, and in 1893 elected him as
one of its associates, an honor accorded to only eight outside of
France. An Officer of the Legion of Honor in 1893, he was
made a Commander in 1907. Tn our own country Professor
Newcomb was very active in the National Academy, in the
American Philosophical Society, in the Astrophysical Society,
and in others. A man delightfully simple in manner and
cordial in intercourse with other men of science, it was always
an inspiration to younger men to converse with him.
C. See
SamuEL Witiiam Jounson, Professor of agricultural chemis-
try in the Sheffield Scientific School of Yale Univer sity, died on
July 2i, in his eightieth year. A notice is deferred till a later
number.
é Vy Un filsivris “5 Rg
Librarian U.S. Nat. Musesin. ;
VOL. XXVIII. | OCTOBER, 1909.
,~ Established by BENJAMIN SILLIMAN in 1818.
THE
AMERICAN
JOURNAL OF SCIENCE, |
Epirorn: EDWARD S. DANA.
ASSOCIATE EDITORS
PROFESSORS GEORGE L. GOODALE, JOHN TROWBRIDGE,
W. G. FARLOW anp WM. M. DAVIS, or CamsBrince,
Proressors ADDISON E. VERRILL, HORACE L. WELLS,
L. V. PIRSSON anp H. E. GREGORY, or New Haven,
Proressor GEORGE F. BARKER, or PuinapetPean,
Proressor HENRY S. WILLIAMS, or Irtwaca,
Proressorn JOSEPH S. AMES, or Battrmore,
Mr. J. S. DILLER, or Wasurineton.
FOURTH SERIES
VOL. XX VITII—[WHOLE NUMBER, CLXXVIII.]
No. 166—OCTOBER, 1909.
NEW HAVEN, CONNECTICUT.
1909.
THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 123 TEMPLE STREET.
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INSET Wo Aa eT
OF
Rare and Choice Minerals,
Adularia, Switzerland ; Apatite, crystal, 24x2, pinkish, Mesa Grande,
Saxony, Connecticut, Tyrol; Alexandrite, Ural Mts.; Argyrodite, Frei-
berg; Apophyllite, Bombay; Arsenopyrite, Freiberg; Amethyst, parallel
growth crystals 2-inch to 6-inch long, Cripple Creek ; Altaite, New Mexico ;
Atacamite, Australia; Bournonite, Nassau, Hungary, England; Boulan-
gerite, Bohemia; Binnite, Binnenthal; Bismuth, Japan ; Cerargyrite, Chili,
Nevada; Chrysoberyl, Finland, Connecticut; Cabrerite, Greece; Cassiter-
ite, Saxony, Bohemia; Crocoite, Tasmania, Ural Mts.; Chloritoid, Tyrol ;
Carnotite, Telluride, Colorado ; Cerussite, Broken Hill; Cuprite, Arizona;
Celestite, Bristol ; Calciovolborthite, crystallized, Telluride, Colorado; Cal-
amine, Ogdensburg; Calaverite, Cripple Creek; Columbite, Conn.; Dia-
monds, loose crystals, Brazil, different forms ; Datolite and Calcite, Bergen
Hill; Eulytite with Bismite, Schneeberg ; Elpidite, Greenland ; Euchroite,
Libethen ; Embolite, Silver City, New Mexico; Emerald, Tyrol, Bogota,
S. A., Ural Mts., N.. Carolina; Hudialyte, Greenland ; Erythrite, Saxony ;
Euclase, Capo do Lane, Brazil; Gold, Hungary, crystallized ; Gadolinite,
Sweden; Herrengrundite, Herrengrund ; Haidingerite, Joachimsthal; Her-
derite, Auburn, Poland; Harmotome, Scotland; Iridosmine, Ural Mts.;
Todyrite, Broken Hill; Ilmenite, Connecticut; Jordanite, Binnenthal ;
Kongsbergite, Norway; Kallilite, Obersdorf; Linnzite, Westfalen; Liy-
ingstonite, Mexico; Lorandite, Maccdonia; Manganite, long crystals, Sax-
ony; Milarite, Switzerland; Mimetite, Freiberg; Monazite, Portland ;
Microlite, Virginia; Meliphanite, Brevig; Neptunite, San Benito; Niccol-
ite, Hisleben; Parisite, Columbia ; Pyromorphite, Ems, Cornwall ; Phar-
macosiderite, Cornwall, Saxony; Pucherite, Schneeberg; Pyrargyrite,
Mexico, Saxony; Pyrargyrite with tetrahedrite, Nevada; Plattnerite,
Idaho ; Pollucite, Paris ; Pseudomalachite, Germany ; Phlogopite, Ogdens-
burgh; Reinite, Japan; Rathite, Binnenthal; Stephanite, St. Andreasberg,
Mexico; Scheelite, Bohemia; Scorodite, Saxony, Cornwall; Smaltite,
Schneeberg ; Sylvanite, Cripple Creek, Transylvania; Stilbite, Bombay ;
. Tiemannite, Hartz; Torbernite, Cornwall, Saxony; Tourmaline, Mesa
Grande, Connecticut, Franklin Furnace ; Tetrahedrite, England, . Hungary,
Utah ; Uwarowite, Ural Mis.: Uraninite, Portland; Vivianite,. Colorado ;
Vanadinite, Kelly, Mexico, Scotland ; Zincite crystals in matrix, Franklin
Furnace ; Zeunerite, Schneeberg ; Zeophyllite, Bohemia; Anatase, Binnen-
thal; Benitoite, San Benito ; Cobaltite, Cobalt, Ontario; Cinnabar, China,
Spain, Adria; Dioptase, Siberia, Fontaineblau, France; Tellurium,
Cripple Creek.
A.A. PE TERE,
81—83 Fulton Street, New York City.
Ey
AMERICAN JOURNAL OF SCIENCE
[FOURTH SERIES.)
——__++9—__-
Art. XX XII.—The Binary Systems of Alumina with Silica,
Limeand Magnesia ; by E.S. SHrrHury and G. A. Ranxin.
With Optical Study, by Frep. Eugen Wricur.
Accorpine to the calculation by Clarke,* the order of
relative importance of the oxides which make up the rock-
forming minerals stands,—silica, alumina, oxides of iron and
lime, ete. It seems desirable to begin with the study of the
systems of alumina, silica and lime, leaving the iron oxides until
more experience with the difficulties of this work should enable
us to meet the increased difficulties which are introduced by
the different oxidation stages of iron. The first paper of the
seriest was published some time ago. We have now to present
the result of experiments with three other groups of oxides.
The interest aroused by the study of the lime-silica series,
not only among those engaged in pure science, but also among
many in commercial work, would seem to warrant devoting
some space not only to the methods but also to the limitations
of this kind of investigation.
In developing a system of such immense usefulness, it is of
the greatest importance that those who are interested in the
application of physical chemistry to extreme cases of rock
magmas shall have a firm grasp of the limitations, both of the
theory and experimental possibilities. None of the laws of
physical chemistry can be applied to such extreme conditions
without some modification.
ae of Geochemistry, F. W. Clarke, Bull. No. 380, U.S. Geol. Survey,
+The Lime-Silica Series of Minerals, Day, Shepherd and Wright,
this Journal (4), xxii, 265, 1906.
Am. Jour. Sci.—Fourts Series, Vou. XXVIII, No. 166.—Ocroser, 1909.
20
294 Shepherd, Rankin, Wright—Binary Systems of
As has often been said, the geologist is dependent on the
petrographic study of rocks which have passed through many
changes. A study of relatively simple two- and three-com-
ponent systems shows the futility of attempting to deduce the
past history of any polycomponent system from its final condi-
tion. Petrographers have already observed the order of
crystallization for certain minerals, but the exact correlation of
this order with the composition of the rock remains to be
determined. The phase rule shows that the first mineral to
separate from a freezing solution depends primarily on the
initial composition and only indirectly on the melting point of |
the mineral. Furthermore, it is always possible for a mineral
to be redissolved after it has begun to separate and sub-
sequently to reappear at a lower temperature. If the eutectic
relation was the only one encountered in the study of minerals,
the classification of rocks, as weli as the interpretation of the
occurrence of the femic and salic rocks, would be relatively
simple. But studies of simplesystems leave no room for doubt
that the phenomena in a great rock magma are exceedingly
complex, and we have no choice but to begin with the labora-
tory study (quantitative measurement) of relatively simple
mixtures of pure minerals. We are entering upon a new
science in which it is absolutely essential that we proceed in an
orderly way through simple relations and conditions to those
which are more intricate. Experiments on the rocks, if under-
taken first, would be as futile as to design a power plant with-
out a first acquaintance with the physical properties of
materials.
Take another obvious instance. It is of course desirable to
know the molecular weight of the various minerals, whether
or not they dissociate in solution, and the effect of these
phenomena on their inter-reactions. At the present time such
questions are practically unanswerable. The molecular weight
of salts im aqueous solution is determined by the lowering of
the freezing point, but even at this low temperature and with
the most delicate apparatus, an error of five per cent is regarded
as doing very well. Not only must the temperatures be
measured to the nearest hundredth of a degree, but the
formule have thus far been found to apply only to “ infinitely ”
dilute solutions,—never over one per cent. Silicate melts are
too viscous to be stirred, and freezing occurs in a region of
variable temperature distribution and always over an interval
of a whole degree or more. Furthermore, we have as yet
no means of knowing that the fundamental assumptions
underlying the Van’t Hoff—-Raoult relation hold true for
silicates. We ought, therefore, to hesitate before forcing the
Alumina with Silica, Lime and Magnesia. 295
results thus far obtained into formule which were deduced
for wholly different conditions and which apply none too
accurately even then. Obviously, the calculation of molecular
weights from concentrations of ten, twenty, and even fifty
per cent, as has sometimes been done, can serve no useful
purpose. ;
A glance at the technique of measurement of conductivity
in aqueous solutions will reveal how unwise are generalizations
based on experiments with the conductivity of silicates. Main-
taining a constant temperature throughout even a relatively
small volume is extremely difficult at a temperature of 1200° C.
Electrodes and containing vessels can not be maintained
constant in shape or dimensions, nor can perfect or constant
contact relations between the electrodes and the melt be
assumed. Until such essential conditions can be supplied, we
cannot hope to derive much useful datafrom merely passing the
electric current through a silicate. The effect of high and
varylng viscosity on conductivity is uaknown.
Pyrometry has made great progress in the last decade, and
for temperatures below 1600° C. the thermoelement is capable
of reading accurately to one-tenth of one degree. But it
does not follow that all thermal phenomena in silicates are
definable with this precision. The phenomena of melting
and inversion, for example, seldom occur with sharpness
enough to allow of their being determined within less than
+=1° for compounds, and +2° for eutectic. We must
guard against the too common error of assuming that we have
determined the phenomena with the accuracy with which we
can read the scale of the instrument.
Above 1600° C. the optical pyrometer must be used, and the
accuracy is much less. Withthe thermoelement the evolution
or absorption of heat which occurs in a charge registers itselt,
leaving nothing to the judgment of the observer. With the
optical pyrometer, as ordinarily used, the melting temperature
must be inferred from the apparent fusion of the charge, and
the observer is dependent upon his arbitrary judgment as to
what constitutes fusion. Usually he cannot determine the
beginning of fusion nor can he tell the exact point where the
change is complete. Here again, not enough is known of the
viscosity of the various mixtures to allow for its effect upon the
phenomenon which the observer sees. As Day and Allen have
shown,” albite retains its rigidity long after fusion (deorientation
of crystal structure) is complete. Quartz acts in a similar
manner. The different concentrations in mixtures show all
gradations between this extreme viscosity and the extreme
*Tsomorphism and Thermal Properties of the Feldspars, Publications of
the Carnegie Institution of Washington, No. 31.
296 Shepherd, Rankin, Wright—Binary Systems of,
fluidity, as in the case of AI,Si0,. The best the observer can
do at present in the region ‘above 1600° ©. is to determine
the maxima and eutectics. Determination of the liquidus is
beyond our present facilities.
There is also a tendency to expect reactions to proceed with
the same dispatch which we are accustomed to meet with in
the case of aqueous solutions. This has not only never occurred
in our experience, but unstable forms often require much urging
to bring them into the stable condition.
The very first difficulty which we encounter is in obtain-
ing pure homogeneous preparations with which to begin. The
natural minerals are rarely pure enough to give constant data.
A natural mineral melts at a given temperature, depending
(as indicated by the Van’t Hoff—Raoult law) upon the amount
of impurity which it chances to contain; but the next speci-
men, having different impurities and in different amount, will
melt at a different temperature. That is, the data obtained
apply only to the specimen examined and furnish no basis for
determining general relations.
The Chemical Purity of the Ingredients.—One must begin
with the purest possible components. The oxides of lime,
alumina and silica on the market are not usually pure enough.
The influence of.small amounts of impurities, 1 to 3 per cent,
cannot. be neglected. <A glance at the slope of the freezing
point curves shows at once that the presence of one per cent of
impurity may cause a variation of five or ten degrees in the
melting temperature.
Calcium carbonate can be obtained very pure, but high purity
cannot be taken for granted without testing it.
The C. P. alumina of commerce is likely to contain °5 to
2°0 per cent of alkalies, and one sample of especially pure (!)
alumina contained over 3 per cent of SO,. Baker and Adam-
son succeeded in making for us a hydrated alumina which
contained only -2 to -4 per cent alkali, and this alkali was then
reduced to less than one-tenth of one per cent by further
purification in platinum.
Pure silica is obtained from quartz, carefully selected with
the microscope, and treated with aqua regia.
Magnesium carbonate usually contains from 1 to 3 per cent
of CaCO,, and this impurity is usually not mentioned in the
manufacturer’s analysis. In this case also, Baker and Adamson
produced a special preparation of high purity.
Homogeneity of the Mixtures.—Atter pure materials have
been obtained, we have next to obtain chemically homogenéous
products. It has been found necessary to melt the charge at
least three times with fine grinding and mixing between the
fusions, in order to obtain a product which is chemically
Alumina with Silica, Lime and Magnesia. 297
homogeneous. A conspicuous visible demonstration of the
need for such careful preliminary mixing occurs with the
composition Al,O, 8 per cent, CaO 69 per cent, SiO, 23 per
cent. As long as the mass is incompletely combined, quantities
of calcium orthosilicate will disintegrate (dust), yielding a
mixture of fine powdered orthosilicate and cinders of the more
aluminous material. After three or four fusions and grindings,
the charge remains solid, i. e., practical homogeneity has been
secured. This shows that diffusion in silicate melts is extremely
slow and emphasizes the necessity for the somewhat tedious
care in preparation.
The effect of insufficient mixing on the observed melting
points may be very great. Even ina sharply melting compound
like anorthite, the cones prepared from the most carefully
mixed oxides often melt 20° or more below those made from
previously combined oxides. Here the heat of combination
is evidently dominant. Obviously, quite the reverse might
happen with other mixtures. One immediate consequence of
this is that experiments in which the Seger cone method is
employed for the measurement of temperature must always be
made with carefully mixed and combined charges. It is also
clear that comparison of the bending of a Seger cone with the
bending of a cone of wholly different mixtures may mean very
little, for the viscosities of the different mixtures bear no
definite relation to each other, and viscosity is the chief factor
in the bending of these cones.* Thus minerals like quartz or
albite will retain their stiffness far above their melting points,
i. e., after their crystalline structure is entirely gone.
Apparatus.—Those portions of the series which melt below
1600° were determined by the thermoelectric method described
in the various publications from this laboratory. Above 1600°
only the optical method described in the lime-silica paper is
available, i. e., an optical pyrometer (Holborn and Kurlbaum
type) sighted on a strip of platinum or iridium. We have
found it useful to make a small tack of platinum, as figured
(fig. 1, B). This tack hasa polished upper surface upon which to
sight. The prepared charge is moulded into a cylinder (A) of
the shape shown; the shaft of the tack
fits snugly into the hole (C) in the Nee Ts
cylinder; the head of the tack (B) rests
firmly on the flat surface of the charge,
while the raised shoulder (D) diminishes
the reflection from the walls of the
furnace. If ideal conditions obtained,
the tack would be invisible, 1. e., we
would have an absolute black body, but
* See The Lime-Silica Series of Minerals, this Journal (4), xxii, 268.
298 Shepherd, Rankin, Wrighi—Binary Systems of
at the melting point the retardation of the temperature of the
charge, communicated along the shaft of the tack, should cause
the head to flash, i. e., become visible. Although the condition
of even approximate blackness is seldom attained in such
furnaces, we were much assisted by this method of procedure.
At the present time observations of melting temperatures
above 1600° are only determinable for the case of compounds
at the maximum, and for eutectic compositions. The course
of the liquidus cannot be established by any optical method yet
devised. For that reason we have sketched all curves above
1600° in dotted lines to indicate that only the maxima and
minima are determined. Of course the phases present along
the liquidus can be determined microscopically, and this has
been done in every case. The method of making these tem-
perature observations is similar to that used on the orthosilicate
of lime. A (fig. 2) is the tube of the iridium furnace ; B, a
magnesia cylinder on which
rests the iridium crucible C.
D is the cylinder whose
melting temperature is de-
sired, with the iridium tack
in position. His amagnesia
@ lid with asmall hole through
which to observe the charge;
F an exhaust tube to carry
away the iridium vapors and
heated air which would
affect the prism H of the
pyrometer. G isan asbestos
shield to further protect the
pyrometer. The bottom of
the furnace is closed by the
circular cup, I, thus prevent-
ing air currents from pass-
ing up through the furnace.
Ifthe furnace acted as a
perfect black body, neither
the metal tack nor the
charge would be visible.
When such blackness does
not occur, the scale of a
theoretically black body does not apply, and the pyrometer
must be calibrated arbitrarily in terms of the conditions in
which it is used. The difference between the theoretical and —
actual scales may reach 100°C. The necessity for frequent
recalibration is also obvious.
ieee
- Alumina with Silica, Lime and Magnesia. 299
This arbitrary calibration of the instrument was made with
the help of certain fixed points. The melting temperatures
of diopside and anorthite are now definitely known, and we
are sure that the melting point of platinum is constant, though
there is some doubt at to its exact temperature in degrees.
We have assumed it to be 1750°. Diopside melts at 1395°,
according to the values of Allen and White,* provisionally
corrected by recent unpublished comparisons with the gas
thermometer by Day and Sosman. On the same curve
extrapolated, anorthite melts at 1542°. By calibrating the
instrument in terms of these fixed points, the relative tempera-
tures of our scale are definitely established. The absolute
temperatures may shift with more accurate determinations of
these fixed points.
The accuracy of the individual observations is determined
by (1) the sharpness of the flash of the tack, and (2) by the
delicacy with which the lamp filament can be matched up
against the tack surface. In this work we found the points
at which the filament was distinctly brighter or distinctly
darker than the tack surface to lie 8 millivolts apart. The
actual adjustment was +2 millivolts, so that the maximum
error of observation was 20° and the probable error +10°
or less. The actual variations in the melting point observed
for platinum were +2 millivolts or 10°. At this temperature,
therefore, the variation due to the material melted falls
within the limits of error of the pyrometric system. The
same is true of the anorthite and sillimanite. We feel
justified in saying that the method is reliable, though rough
and of limited usefulness compared with the thermoelement
below 1600°. Several improvements have been suggested by
this work and are now being tested.
Preliminary studies for locating the approximate position
of maxima and minima were made in a 40™™ iridium tube
furnace (Nernst type) by placing small amounts of the finely
powdered and thoroughly combined charge on an iridium tray
and exposing for a definite period at constant temperature.
This temperature is then increased by degrees until the
minima appear, after which the temperature is stepped up
until the maximum is located. With sharply melting mix-
tures, and where there is a reasonably large difference of
temperature between the maxima and minima, the compositions
can be quite definitely determined. If, however, the eutectic
is viscous, like that between AI,SiO, and SiO,, the minima
can be located only approximately by this method. Similarly,
where the compositions of the maximum and minimum are
*This Journal (4), xxvii, 1, 1909.
300 Shepherd, Rankin, Wright—Binary Systems of
close together, like Al,SiO,-Al,O,, and the temperature dif-
ference is small, the exact location of the eutectic composition
is very difficult to establish. Unfortunately, the microscope
is also of little assistance in this case.
All such observations must be made in an oxidizing or
neutral atmosphere; a reducing atmosphere not only reduces
some of these oxides and silicates, but even where this is
not the case, the flame playing about the furnace opening
renders the optical pyrometer useless for exact measurements.
A. hydrogen atmosphere is perhaps the worst. At tempera-
tures above 1000°, it reduces silica or silicates, settmg free
silicon which renders the platinum or iridium crucibles “ hot
short” and ultimately destroys them. This reaction is
doubtless due to the silicon hydride, since it is by no means
necessary that the silica and platinum be in contact in order
that this destructive action occur. A platinum erucible in
which a charge of silica was heated to 1100° in hydrogen,
increased in weight by more than thirteen milligrams. On
analysis, almost the theoretical quantity of SiO, was found.
The crucible was highly crystallized and could be broken up
to a coarse powder in the fingers. Wires less highly charged
with silicon are very brittle when hot, even though not
appreciably so when cold.
Carbon is known to react readily with lime above 1700° to
give calcium carbide, so that a carbon atmosphere above 1200°
introduces an undetermined error into the work.
One of the series studied (lime-alumina) presents the
troublesome case of a compound unstable at the melting
point. If the composition of
BCE the compound be X (fig. 3),
then the first crystals to separate
on the freezing of this mixture
are, of course, B. At the tem-
perature ¢, these crystals should
combine with component A to
form the compound AB. But
it often happens that the erys-
tals become coated over with
the compound AB and are
thereby removed from the action
of component A. ‘The result is
that the charge freezes at 7, to
a mixture of A, AB; jamd@is,
which of course is unstable in
a two-component system. Theoretically, if the charge were
held for a long time at a temperature between ¢, and ¢,, dit-
fusion should cause all free B to disappear, so that the mass
A
Alumina with Silica, Lime and Magnesia. 301
when cooled down should consist entirely of the compound
AB. By taking the fused charge of composition AB, grind-
ing to a very fine powder and heating for a long time between
temperatures ¢, and 7¢,, we were successful in bringing about
this reaction in the case of 3CaO.A1,O,.
Alumina-Silica.—In this series there is but one compound
which is stable in contact with the melt. This is the mineral
sillimanite, Al,Si0,, composed of AJ,O, 62°85 per cent, SiO,
3715 per cent. This occurs in nature widely distributed.
The same compound has been found by Mellor in the crystal-
lized glaze of porcelain. The pure artificial compound is
colorless and occurs in well crystallized prisms of density of
3°031, slightly lower than the natural mineral, which averages
3°32. Hardness is 6 to 7. The compound is unaffected by
water, hot or cold, and is but very slowly attacked by acids
or alkalies. Sillimanite is practically unaffected by HCl,
HNO, or H,SO,, hot or cold, or by cold HF. It is decom-
posed slowly in mixed HCl and HF, and by fused Na,CQ,.
The melting temperature of the pure compound is 1811° C.
A Ae Tan
a. Melting point fused b. Melting point of mixed and
sillimanite made from heated oxides of the same
pure oxides. composition as a.
Millivolts T Millivolts T
"475 Lt "472 1802”
"AT5 1812 "485 1850
“474 1810 "483 1850
‘474 1810 "483 1850
Mean 1811° “479 1833
"480 1835
Table I, 6,is given to show how great an error is introduced
by observing incompletely combined oxides. These charges
had been heated several times to about 1600° in the gas fur-
nace, but still showed free silica and alumina. After fusion,
they gave concordant results. The flash is also much sharper
when the oxides are properly combined. It will be noticed
that the observed melting temperature varies irregularly, and
is not altogether dependent upon the rate of heating.
The eutectic Al,SiO,-SiO, is very hard to place, owing to
the extreme viscosity of the silica. Heated for one hour at
1550° in a platinum furnace, nearby mixtures show no evidence
of fusion. The 15 per cent and 20 per cent AJl,O, charges show
traces of fusion before pure SiO,. The eutectic must there-
fore fall at about 10 per cent and melt slightly below 1600° C.
Throughout the range of concentrations from SiO,to Al,O,.Si0,
302 Shepherd, Rankin, Wright— Binary Systems of
cristobalite and sillimanite are the only phases. The eutectic
for Al,SiO.—Al],O, is only very slightly below the melting tem-
perature of the compound. There is, however, a rapid rise of
the liquidus beyond 65 per cent A1l,O,, so that in default of a
pyrometrie method we must depend on the moditied Joly
method which indicates the location of the eutectic at about
64 per cent AJ,O,. |
Corundum occurs in all compositions between AJ1,8i0O, and
AJ,O,, and no phases other than sillimanite and corundum do
appear. The optical properties of the silimanite remain prac-
tically unchanged in the presence of SiO, or Al,O,. We
accordingly infer that little or no solid solution of the com-
ponent minerals in sillimanite occurs here.
The corundum shows slightly altered properties, and proba-
bly takes up a limited quantity of sillimanite in solid solution.
The melting point of corundum hes above the safe working
range of the iridium furnace, and it is hardly worth
while to attempt determinations in the carbon furnace. The
nature of the equilibrium diagram is shown in fig. 4.
Fig. 4.
2000°
£800°
SiO, Al,Si0; Al,O3
Unstable forms.—The two natural minerals of the same
composition as sillimanite are cyanite or disthene, and anda-
lusite. Neither of these minerals occurs in igneous rocks and
Vernadsky has shown* that both change to something like
sillimanite at temperatures above 1300°. He also states that
the change is accompanied by an evolution of heat. We have
verified the change of form, but have not been able to detect
any heat change. Our experience led to the conclusion that
* Bull. Soc. Min., xii, 446; xiii, 257.
Alumina with Silica, Lime and Magnesia. 303
the inversion takes place so slowly as to completely veil the
character of the corresponding heat change.
A very pure andalusite from Hill City, 8. D.:
Heated Temperature Remarks
48 hours 1100° Unchanged
(Tes ae ILO és
ToS ze * 1150° a
28 days 900° ie
fs 1500° Much altered
If the transformation is reversible, the change is slow even
at temperatures much above the supposed inversion point. All
natural andalusite is contaminated with mica which masks
the reaction. Using a flux in the hope of getting the trans-
formation at lower temperatures, failed to yield satisfactory
results. .
Time Flux Temperature Remarks
12 hours NaCl 800° Little altered
ie ag es gs Andalusite still abundant
EGS: << a S Andalusite still abundant. No
sillimanite
moe CaV.O. _1000° Andalusite still present. No sil-
limanite
ae, i 900° Little changed. No sillimanite
mG. es 900° Little changed. No sillimanite
At higher temperatures the andalusite is decomposed with-
out forming sillimanite. Andalusite heated seven days at 400°
in a bomb containing 10 per cent NaCl solution showed no
change. The result indicates that andalusite changes to sil-
limanite at high temperatures, but with considerable diffi-
culty. The reverse change, sillimanite-andalusite, does not
occur under any conditions which we have yet tried.
Cyanite,—Like andalusite, cyanite is much contaminated
with mica, rendering satisfactory thermal study of the natural
mineral difficult. It is not possible to separate it completely
by purification with aqua regia and cold HF. Its specific
gravity is 3°5 — 3-7. Hardness 4-5 or 6-7, depending on
the direction with respect to the prism axis. Vernadsky
found the mineral changing to sillimanite above 1300°. We
have found the change to be slow, though more rapid than
the change from andalusite to sillimanite.
Time Flux Temperature Remarks
$+ hour None 1500° Decomposed, but no sillimanite
identifiable
7 days € L150" But little changed
7 a 1150° But little changed
wer % 1000° Unchanged
ae se 900° Little changed
Borax decomposes the mineral.
304 Shepherd, Rankin, Wright—Binary Systems of
Time Flux Temperature 'Remarks
12 hours NaCl 800° Unchanged
We ae ‘i 800° Little changed
48 £ * Cave Mo00s Cyanite decomposed but no sil-
limanite formed
Cyanite is thus more readily decomposed than andalusite, but
shows no sillimanite which can be determined with the micro-
scope. :
We have shown that at about 1300° both andalusite and cya-
nite change, the one into sillimanite and the other, from
Vernadsky’s density determination, probably into sillimanite,
though badly formed. It is now in order to determine whether
sillimanite, which is stable at high temperatures, will change
into cyanite or andalusite at low temperatures.
Sillumanite shows no heat effect between 1100° and 1500°.
Time Flux Temperature Remarks
168 hours None 600° Unchanged
Gears Pe 1100° Unchanged
Heated four days at 1000° with a small amount of borax, the
crystals sbow slight attack, but are not destroyed, and no
andalusite or cyanite appeared. Heated 48 hours at 1100°
with CaV,O,, ‘the powdered crystals were slightly attacked
and new crystals of sillumanite formed. Working in steel
bombs with various aqueous solutions, negative results were
obtained.
Time Flux Temperature Remarks
7 days 5% NH,F 400° The original grains are pitted,
but no new crystals formed
Gis 10% NaCl 450° Unchanged
ee a 10% KBr 400° Slightly attacked
Heated thirty days in a long steel tube which allowed a con-
tinuous current of hot water (250°) to pass over the mineral
and then to a cooler part of the tube, no alteration was pro-
duced.
Thus at low temperatures no conditions were found under
which sillimanite tended to change into andalusite or cyanite.
Solutions of sillimanite in albite and borax gave always sil-
limanite. When fused sillimanite is rapidly cooled (quenched);
it always crystallized as sillimanite.
It would be a waste of time to tabulate all of the metatheti-
cal reactions by which we have sought to produce these two
unstable forms. After overcoming the great difficulties of
finding a suitable vessel which will withstand the pressure of
aqueous solutions at high temperatures, and which will not be
Alumina with Silica, Lime and Magnesia. , 305
attacked by the reagent, we have not yet been successful in
our attempts to prepare andalusite and cyanite. Attempts to
produce reactions between the hydrated oxide of silicon, i. e.,
the various hypothetical silicic acids, and alumina, hydrated
or dry, gave no positive results. Certain reactions involving
the attack upon anorthite and other minerals by A1,(SO,), or
AICl,, have yielded but little promise of success. AICI, acting
on anorthite gave small spherulites of which the determinable
properties agree with andalusite, but these crystals were too
small for positive identification. We did not obtain positive
results by the action of fluxes on the oxides.
Incidentally, we observed the formation of meionite by
crystallizing glass of that composition in a bomb with 10 per
cent NaCl solution, and SEG by the reaction of AlCl,
on calcium orthosilicate.
Sillimanite glass.—Sillimanite melts sharply to a very thin
liquid which crystallizes with great rapidity. Dropping the
crucible of molten sillimanite in water does not cool even a
small charge rapidly enough to prevent
crystallization. We used the system
shown in fig. 5. A is an iridium
erucible with a 3™" hole in the bot-
tom. It is supported in the furnace
.tube, E, on a magnesia ring, B, which
is In turn supported by small mag-
nesia rods, C, and the ring, D. The
melted charge drops from the tip of
the cone directly into the dish of
water, F. In this way we obtained
a number of globules of glass, with
an index of refraction of about 1°625
and a density of 2°54, much lower
than sillimanite. When crystallized,
either by heat at 1200° or in bombs
containing 10 per cent NaCl solution
at 350°-400°, the glass yielded only
sillimanite. It seems reasonably cer-
tain that sillimanite is the stable form
and that andalusite and cyanite are
formed by erystallization from solu-
tion at low temperatures.
Lime-Alumina.—it is much more
satisfactory to deal with systems in
which at least a part of the liquidus
can be definitely located with the
thermoelement. From about 15 per cent to 70 per cent of
alumina, this series can be melted in platinum and all of the
3806 Shepherd, Rankin, Wright—Binary Systems of
eutectics with the exception of 3CaO.5A1,0,—Al,O, can be
precisely located by means of the thermoelement. The study
of this system with the microscope shows seven phases in
addition to the two components. The phases are CaO.A1,O,,
5CaQ.3Al1,0,, 8CaO.Al,0O, and an unstable form of both
3CaO.5Al,0, and 5CaO.3Al,0,. The equilibrium diagram
is shown in fig. 6.
Fie. 6.
7
Ve 4
ip
/
Wy /
1700° \ p Mee est On
\
N
\
\
1600° ‘i le ee
\
ON
6 =f
5 o fame
1500°
1400° ¢ |
mR Fe Ss Nite mes
|
CaO 3CaO. Al,O3 Al,O3
CaO. Al,Os3
5CaO.3A1.03 3CaO0.5A1.03
The approximate melting temperature of lime is not known,
except that it melts in the arc. The optical and other prop-
erties were given in the lima-silica paper to which reference
has been made.
There is no eutectic between lime and the first compound,
3CaO0.Al,O,, at 87°78 per cent of alumina. The compound
being unstable at its melting point, the liquidus must show a
Alumina with Silica, Lime and Magnesia. 307
change of direction, but not a minimum. There is, however,
an inversion temperature along the line L, where both CaO
and 3Ca0.A1,O, separate at the temper ature 1531°. For con-
centrations between L and B the lime which has erystal-
lized combines to form 8CaQ.Al,O,. Along the liquidus
BC, 3CaO.A1,O, is the stable phase. In practice, the time
factor is a very important one in bringing about these reactions
and some lime always becomes surrounded by erystals of the
compound, so that the next phase, 5CaO.3Al,O,, also occurs.
This renders the eutectic observations along NO more irr egular
than they would otherwise be and, as the diagram shows, the
eutectic, C, occurs as far over as M.
In order to prepare the pure compound 8CaO.Al,O,, it is
necessary to bake the charge a long time at about 1400°. This
allows diffusion to occur with the elimination of the excess of
CaO and 38Ca0.5Al,0, Experimentally, we found that
the 37°78 per cent charge, held 21 days at 1400°, was free of
the excess phases. Similarly, the compositions 35 per cent,
34 per cent and 32 per cent of Al,O,, when merely fused and
erystallized, without the long exposure, show 3CaO.A1,O,
with CaO and 5CaQO.3A]I,O,, but were transformed into CaO
and 3CaQ0.Al,0O, by heating at 1400° for the same length of
time. In order to accelerate the reaction, we took the pre-
viously fused charges and ground them to a fine powder before
starting the heat treatment. Such cases as this are not
uncommon in silicate melts and the investigator must bear
them constantly in mind or he will be led far astray.
The compound 3CaQ.A1,O, is isotropic, with density 3:038
for the annealed material. It is readily attacked by water,
either hot or cold, and dissolves quickly in dilute hydrochloric
acid.
The eutectic (C) between 3CaQ.Al,O, and 5CaO.3A1,O, at
52°22 per cent occurs at 51 per cent Al,O, and melts at a
temperature of 1382°.
The eutectic (KE) between 5CaO.3AI,0, and CaO.Al,O,
oceurs at about 53 per cent Al,O, and 1882° C.
D is the maximum corresponding to the compound 5CaO.
3AI,O, at 52°22 per cent Al,O,, which melts at 1386° C. The
maximum is so close to the eutectics, both in composition and
temperature, that a precise determination is difficult. It is
isotropic, has an index of refraction of about 1°61, anda
density of 2°828.
This compound also occurs in an unstable form which is
birefracting, but always changes into the isotropic form when
given an opportunity to do so.
Between 40 per cent and 60 per cent AJl,O, a number of
very small irregular heat effects were observed. It was
308 Shepherd, Lankin, Wright—Binary Systems of
necessary to determine whether or not these changes were in
any way related to the stable phases present in this region.
Quenching experiments made by removing
aes the charge from the furnace and chilling in
water were found to be too slow. Obviously,
a { 0 from a field like E F O, where we have the
E phase CaQO.A1,O, in contact with the melt,
great speed in cooling is necessary to prevent
the whole mass from crystallizing in the
presence of the excellent nuclei furnished by
HTT Ie the solid phase. Therefore a special device
SSSIS|| | [RSS was needed to secure more rapid cooling.
A The system adopted is shown in fig. 7.
: Passing throngh the furnace is a tube, A.
Zi) Za Within this inbox is placed the element, Ki:
The charge is contained in a small platinum
cup, b, suspended by a small porcelain ring
from the fine platinum wire, C. This wire is
attached to two heavy platinum leads marked
+ and —. The tube isclosed at the bottom —
by the removable plug, D. F is a dish of
mercury with a layer of water above it. In
Nc |} f. operation the charge is brought to the
desired temperature and held for a suitable
° length of time. The plug D is removed and
a strong current passed through the wire C.
one I The current fuses the wire, vane ing the
— —- charge into the vessel, F. The aoe
D ring C prevents the wire of B from sticking
ASSEN to the suspending wire at ©.
By this method we were able to quench
ein mae samples of the partly melted charge, obtain-
f ing well-formed crystals of the primary
phase imbedded in glass. In other words, we were able to
bring the charge to room temperature rapidly enough to pre-
vent its changing over. The results of this study are given
below: Zime is the time during which the charge was held
at the temperature, 7, before ~ quenching; J, traces of
unstable form of 50a0.3A10, ; [| present; 77, trace.
©4220 F829 ©0600 © eevee de
e
wh >
Time ih Glass CaO 5Ca0.3A1.0; IB 38CaO.AlZO;
( 30min. 1544° II I| I| I| I
ue tail I| II I| I 2
Gig 1487° I| I| || = en
41% AloOs ~ 60 ‘ 1457° Bt I| I| | I
30) 1454° ex | | I I
60 << 1427° ok I| | i I)
L 90 <« (3942 Peles l l ue
Alumina with Silica, Lime and Magnesia.
Time
30 min.
ce
ce
|
44¢ A1,05 { ;
a
47% Al.O3
60 min.
60 <<
05 ¢
ef | 60 *
1% 41,0 ?
ee) 20
| 30 66
1
“é
‘eé
| sc
60 “é
lL
di Glass
1544°
1513°
1484°
1454°
1425°
1425°
1394°
1394°
di
1535°
1535°
1530°
1527°
1531°
1520°
1520°
1520°
1520°
1506°
1506°
1598°
1491°
1484°
1476°
1458-52
3CaO. Al.O3 IB
IB
3C0aO 5 Al,O3
38CaO. Al,0;
I
|
309
3CaO - Al,O3
dCaO . 3A1,03
5CaO. 3A1,03
Am. Jour. Sci.—Fourts Series, Vou. XXVIII, No. 166.—Ocrossr, 1909.
21
310 Shepherd, Rankin, Wright—Binary Systems of
3CaO.
Time AQ Glass IB ~ Al,Os 5CaO.3Al1,03; CaO. Al,O3
( 80min. 1565° \| at
|
|
a TNE} ll &. vie a Wo
52.22% 4 as 1484° II oes Vif. le =
Al,O By 1454° I| Bess ao op oe
| 4 1424° I| ee ae I| tr
ie ee 1394° I| ter neers I| lI
( es 1544° II ae ile ai a
3 doit 2 II DSS ae a ig
| ce 1484° II Mes re ae ea
53% Al.O3 4 as 1454° I| 5s Si tr ba
| es 1427° II a Bek I| I|
60 * 1431° I| ae ie I|- II
(ears Olga LSSoiiee 2 ee 3 II I
( be 1304 ee pe ae I| I|
| de 1424° I| ae a ee I|
; ei 1458° I| oe oe le |
50% Al.O3 4 (3/2 1486° \| th Be fat wed,
| 3 1513° || a a fis Re
L ef 1544° I| a ee ah eee
Time ae Glass IB oCaO . 8A1,05 CaO. Al.Os
( 30min. 1894° ae 23 | I
| ‘3 1428° I| 8 II l|
| eo 1454° I| us eee I|
51% AlzOs + “ 1484° | A ss I
| oe 1513° I| Ans we I
| es 1544° I| ac tr tr
( 45° 1544° l| || zs II
| BO) oe 1513° | II ae II
12055. olor I| Tl 2 I|
| i oils | oe a I|
Wess “ 1454° 6 a |
| 340) oe 1424° I| ve I| II
180 ‘‘ 1424° mes be | I|
es Let) 29 1394° ei PS I| II
Examination of this series of quenchings shows that the
birefracting phase, which was found to be homogeneous at 52°22
per cent Al,O,, is not present as a stable phase. . It appears in
small amounts (indicated by IB) in certain quenchings and not
in others. It usually occurs in mixtures where a large charge
is taken from the furnace and air-cooled. It appears in the
same charge along with the stable phase, but disappears when ~
the mass is baked at 1300°, passing into the stable form. The
heat effects due to this unstable form occur irregularly both
as to temperature and time of development. They are
destroyed by holding the charge just below NO for a time.
before making the heating curve.
The spinel analogue CaO.Al,O, melts at 1587°. It has a
density of 2981. It is a birefracting crystalline substance,
Alumina with Silica, Lime and Magnesia. 311
attacked slowly by cold water and readily by hot. The
densities of all of these aluminates were determined in dry
turpentine at 25° and reduced to water at 25°=1. Hydro-
chloric acid dissolves all of these compounds.
The eutectic CaO.Al,0,—3CaO0.5Al,O, is located at about
67-5 per cent Al,O,. The liquidus falls but slightly from 65
per cent to 67°5 per cent, the temperature of the eutectic being
1580°.
At 75:22 per cent the preparation is homogeneous. The
melting point, determined optically, is:
Millivolts 4h
"452
ee 19)
Al,O, a ee 15 22 | °455 ryan
AD,
2 .
ca) heen 24 78 | a
There is a second crystal form of the 83CaO.5A1,O, compound
which shows different optical properties and a specific gravity
of 3°05, determined by flotation. It seems probable that the
relation of the two is monotropic, though the speed with which
this higher form changes into the lower, together with the
high temperature, makes quenching experiments unsatisfactory.
Crystals of the low form usually show indications of having
inverted during cooling, while preparations quenched from
above line GP do not. GP is an inversion point, and as it
extends to h, indicates that the 75°22 compound is unstable at
its melting point. In the iridium furnace, the 75:2 per cent
Al,O, preparation seems to melt before the 76°5 per cent.
This means either that the 3CaO.5AI,O, is unstable at its
melting point or that the eutectic is so close to the maxi-
mum that the necessarily crude method will not determine it.
The evidence indicates the former relation and we have
adopted it. The 76°5 per cent Al,O, shows free alumina, as
do all preparations between this and 100 per cent AlJ,O,.
Taste I].—Invariant System Ca0+38CaO.Al.03. (Line S L B, Fig. 6)
l l
Percentage) ob) aes
of ALO, | 10 190 20
(i)
OU
28 |31-29| 35 [87-78] 41 | 42 | 43
Eutectic
melts_--|/1526° 1524°}1530¢ |1536° |1531° |1535° |1534° |1535° |1548°/1529°|1535°
8 6 ;
2 ti soos oo SG) | 391 Seah aes o4e) adel | 34
ee mates een SS etna aaa aera | |. 35
Bee aa eR lee ee
Mean. 2=-} 1528 |1526 1529 1536 (1532 1536 |15384 1534 1537 1531 |1534
312
TABLE III.—Eutectic 3CaO . Alo.O2, +5CaO. 3A1,03.
Shepherd, Rankin, Wright—Binary Systems of
Percentage
Al.O3
Eutectic
melts ___|13883°)1383°
51
1384
50 | 49 | 48 | 47 | 46
1386°)1886°|1382°)1387°
84; 80; 838/ 85; 8)
TOL sl ees oy a)
So |) ol V7 4a 382 cl
VS OO eSOy et = Sites
Cl C2 sie Soules,
Ha Ne SOO C2 ae eae
18 eo Sot | ee ans RO
UT an re eres en EAH
Teo ee ue ete sine ek Se Neacess)
A A a eeeeina OO)
Bate ge ele gsi ee 2 ols)
1379 1383 |1382 1883 |1382
(Line T N M)
45.| 44 | 43 | 42 | 4037-76) so 3129
13885°|1884°|1387° |1884°|13877° |1377°|1874° |1380°
81 |: 83 |. 86 | 86.) C2 aie on se
80 | 82.) 81). Sl 7On aii eee
S1 | 78 | 2) ee es a ee
AO | NOS) Dees Me Bg pe on, 2 Ae
SBS CO eas he Bere) |e ne
Eel er O Oty oeeee wet | oe ee ee
wo | 208 | 22a eee Se ese 2
1381 [1382 |13885 1884 1379 |1377*|/13875*/1381*
* Kutectic points occurring beyond 37°78 composition, due to failure to reach equilibrium.
TaBLE IV.—Eutectic CaO. Al,0;+5CaO. 3A1,0;. (Line T O)
Percentage of Al.O; 60 d9 57 56 55 54
Eutectic melts ---.-- 1384° 1388° 1381° 1388° | 1590° | 1884°
site a 86 79 82 83 81
wanes 83 78 81 80 82
whe 78 78 81 80 82
Bi 83 84 81 78 86
rey 60 89 79 83 88
atte as 79 88 89 80
eee! ao 82 oe se val
Tee os 78 re ae pie
228 Ue 79 ae Sr ae
Midamitses sales cee 1384 1382 1380 1885 1383 1883
TaBLE V.—Melting Points.
Percentage! 69 | 57 | 50 | 46 | 45 | 44 | 43 |) 42 | ai eiereletee
of Al,0O3
Melts___.. 1473° |1467° |1458° 1435, |1446° 1480°|1454°|1455°|1426° 1427° 1458°
V5 |) V7 Ad) 894)" 88 | 129) 9-36 | ol a28 me
68 | 62 | 53 | 389°) 24) 28 | 34:) Ol |) 21) aos aes
_. | 58 | 4510 38 | 380°) (475) 3845-49) 2 Se ee
us a eS SO ee 4 |) CA OO aaa = lo BS
a Sys Mies vepike all Pace) an ce Or ea shes a! | eee
ys he eoelhs SQiuale Boi gall sae An Es 2 aay
ke ae ue (ails oO lea ee Be. oe se a |) ae
oe a Se Reha eee 2 ue ce! ras, | eee
sah id 2 el a eee a) fie Ns 2 ea
ns Ba hae a1 GciPy wits nee ae e |e
Mean.---- 1470 1466 1450 1429 1431 1437 |1440 |1452 |1425 |1486 |1454
Alumina with Silica, Lime and Magnesia.
TaBLE VI.—Curve of melting points.
313
(Curve A, B, C, D, E, F; G, H)
Percentage of |75.09/7-5 |e4-58| 60 | 59 | 57 | 56 | 55 | 54 | 53
Al,0O3 x |
Component in
excess melts _,1710°|1581° |1587° 1568° |1537° |1495° |1444° 1458° |14438° |1889°
Soe eee eee 66 | 48 1500 | 54 | 638 | 385] 85
Oye ae a GON SOs MAGS? | OnE R a e 3 le.) OK.
eee oo Ode eA. 98) | SOO ta Oo | OO
ise hes er OOn ss AS ties | AB ICE Oe Oe
ee es hos sl Or he AQy ge rl eens ell 2 OO |e
oh ea eae Oe A es leg ES by AD eee
Mieamn ee ot. 1710 |1581 |1587 |1566 |1547 |1498 |1449 (1461 1487 |1386
Percentage of s | |
ALO, 02°22) 51 | 49 | 48 | AY | 46 | 45 | 44
Component in | |
excess melts -|1587°|1383° |1429° 1485° |1440° |1480° |1495° |1525°
905 283) 2 420m" 365). C40" | -79))-7 93.) 24
SOM ol eee ONiae coe toon) seri 90. «20
CAR Sa teed los dori (oOn | Olah 97 alnauss
Sans Of |eugou|s Soll Fol) Sa SOG. 2s
Ba C4 S20 r is 28 [ee BOATS A" bees
= = ler oon ae ee aa EE aes
g ak Rae oo lat dese ae ae es
oy Se Se letras ba ae oe Be
Bia ek. 1386 |1384 |1424 |1482 11488 (1481 |1494 |1525 i
* Determination in iridium furnace with optical pyrometer.
TaBLeE VII.—Eutectic CaO. Al.03; +8Ca0O.5A1.0;. (Line G R)
Percentage A1,0O; 67°5 70 73°22 74-2 79°22 76°5
Kutectic melts .-_--. 1581° 1582° 1582° 1578° | 1577° | 1972°
1579 1574
1574
Ed Tie aa Se a tosie + 10827 1582° LOS eee 15 78ers lien
The Al,O, melts too high for safe determination in the
iridium furnace.
Apparently, some 3Ca0.5A],0, crystallizes
with the alumina since its optical proper ties are slightly
changed, but we have been able to detect CaO.A1,O, in the
95 per cent mixture, so that the range of this solid solution is
less than five per cent.
Lime-Magnesia and Magnesia- Aino — While the melt-
ing temperatures of both of these series lie beyond our present
314 Shepherd, Rankin, Wright— Binary Systems of
methods, we have made some preliminary fusions in order to
ascertain whether or not compounds formed between them.
It was necessary to use a furnace made of the purest artificial
graphite, the cone being supported on a graphite block which
did not form a part of the furnace resistance.
It was found that in all fused mixtures of CaO and MgO the
two oxides crystallized out side by side, showing no evidences of
combination, from which we conclude that there is no compound
between the two. These temperatures are beyond the working
range of the iridium furnace. Even with the purest graphite,
small amounts of silica will get into the cones, giving a small
amount of birefracting material which is identical in all deter-
minable properties with Mg,SiO,. This would seem te account
for the birefracting material sometimes found when these
oxides are fused in the are. The amount of this birefracting
substance was independent of the nominal composition.
The location of the eutectic was rendered uncertain because
of the attack on the lime by the graphite.
Magnesia-Alumina.—This series, melted in graphite, gave
one well-formed compound, MgO.A1,O,, similar to the lime-
alumina series. There was no other compound formed.
Between 0 per cent and 71°6 per cent Al,O,, the solid phases
are MgO and MgO.Al,O,. Between 71-6 per cent Al,O, and
100 per cent Al,O,, MgO.A1,O, and AJ,O, are the solid phases.
The melting temper ature of the MeO— -Mg0.A1,O, eutectic
is at about 1950°.
These last two series are given only for the purpose of
guidance in calculating the possible effect of small amounts of
magnesia, which in commercial work are always present in the
lime-alumina-silica mixtures. In time, some one may devise a
furnace and containing vessel which will allow their more
precise examination.
The results of the present thermal study may be summarized
as follows:
1. There is but one compound (A],8i0,) of alumina and
silica stable in contact with the melt. This is the mineral
sillimanite. The two minerals andalusite and cyanite pass
slowly into sillimanite on being heated above 13800° C.
2. There are four definite compounds of lime with alumina,
namely, 3Ca0.Al1,0,; 5CaO.3A1,0,, melting point 1387 C.;
CaO. Al ,O,, melting point 1587° C.: 8Ca0.5A1,O,.
3. 8Ca0.Al, O, and 3CaQ0.5A] 0, have no true melting
point, but the former will i completely melted at about 1550°
and the latter at about 1725° C.
4. Two of these cami ponne 5CaO.3A1,O, and 8Ca0.5A1,0,,
have an unstable form each, while 30a0.A] ,O,, and probably
3CaO.5Al,0,, are unstable at the melting point, i.e., do not
produce a maximum on the liquidus.
Alumina with Silica, Lime and Magnesia. 315
5. Of these aluminates it seems probabie that only 3CaO.
Al,O, will occur in portland cement.
6. There is one compound, MgO.Al],O,, between magnesia
and alumina.
7. There is reason to believe that the system MgO-Ca0O is a
eutectic series with no compound and little if any solid solution.
The temperature range is too high for satisfactory investi-
gation.
Having established the nature of the binary systems, experi-
mental study of the ternary system CaO-—A1,O,—Si0, is now
under way.
Optical Study ; by FRED. EuGENE WRIGHT.
In the foregoing pages the general problem of the lime-
alumina series has been considered in detail, the different com-
pounds in the series have been described and their stability
relations at different temperatures discussed ;. in brief, all data,
chemical, thermal and optical, which bear on the problem, have
been used, and the conclusions reached are based on the entire
evidence at hand. Im this treatment of the problem, its
physico-chemical aspects have been especially emphasized
because the established generalizations of physical chemistry
best explain and define the limits in the relations of the com-
bining minerals, and such data are of fundamental significance
in the general study of rock and ore genesis. A restatement
of the entire lime-alumina problem from the optical standpoint
with the thermal and chemical data as confirmatory evidence,
although possible, is, therefore, deemed unnecessary, and in the
following pages only the detailed optical description of the
different components of this series will be given, followed by a
brief account of the character, significance and interrelation of
the different kinds of experimental evidence which require to
be brought to bear upon such problems of petrogenesis for
their effective solution.
Calcium Oxide.—Crystals of this substance were not pre-
pared especially for this investigation, since its optic properties ©
have been described in detail in a former paper.* Free lime
crystallizes readily in the isometric system, is isotropic and
occurs in the different preparations of this series in the form
of rounded grains. A remeasurement of the refractive index
by the immersion method in a liquid consisting of methylene
iodide, arsenic bromide and arsenic sulphide, was made, and the
index found to be 1°832+°005. The high probable error is
partly due to the lack of distinctness of the phenomena
observed and to the slight attack of the lime by the solution
itself.
* This Journal (4), xxii, 294, 1906.
316 Shepherd, Leankin, Wright—Binary Systems of
The most interesting fact with respect to the lime which has
come to light in the course of this investigation is the evident
erowth of the grains at temperatures above 1300°. Fine
impalpable powder resulting from the calcination of calcite
was heated for a week in the electric resistance furnace at
1300°-1400° and found at the end of that time to consist of
rounded grains of lime measuring as high as -01—02™™ in
diameter in place of the submicroscopic material which went
into the furnace. This temperature is 1000° or more below
the melting temperature of crystallized calcium oxide,
and yet at ordinary atmospheric pressure and in the dry state
crystals of calcium oxide grow rapidly at 1400° and resemble
in all respects those formed out of melts of different composi-
tions. This principle of causing crystal growth many degrees
below the melting point and in the dry state is being
applied constantly in this laboratory to render fine microscopic
preparations suitable for optical examination. Experience
thus far gained has shown that not all compounds grow with
equal rapidity under these conditions, and in fact free alumina
seems to be little affected by this treatment. The growth of
calcium oxide crystals under these conditions is, however,
definitely established, and is an important fact to be taken
into consideration in connection with crystal formation and
growth.
The 3Ca0.Al,0O, compound: CaO 62-22, Al,O, 37°78.—
Preparations of this composition have never been obtained per-
fectly homogeneous and free from grains of free lime and also
of the lower refracting 3CaO.5A1,O, compound. The amounts
of the latter, however, are not large and their presence has
been shown to be due to dissociation. Optically this compound
is simple in its properties. It crystallizes in the isometric
ee and exhibits no pronounced cleavage. Jndications of
cleavage after (111) or (110) were observed here and there, but
only imperfectly developed. The fracture is conchoidal; the
hardness is about 6. Although no separate crystals for gonio-
metric measurement could be obtained, the frequent hexagonal
and rectangular outlines of the grains in the thin section
indicate the rhombic dodecahedron (110) or octahedron as the
predominating form. The grains are colorless, of glassy
luster, and isotropic, with refractive index n,,—1°710+°001
measured on the Abbe total refractometer. Occasionally faint
gray interference colors were observed on certain grains and
were evidently due to strain. No definite arrangement of
inclusions or zonal growth was noticeable, even on the largest
grains, measuring 0-1™™ in diameter.
The 5Ca0.3Al,0, compound: CaO 47°78, Al,O, 52°22.—
Separate crystals of this compound were not obtained and no
Alumina with Silica, Lime and Magnesia. 317
distinet cleavage was observed, either in the crystalline powder
or in the thin sections of the different crystallized melts. In
the thin section, however, minute inclusions, apparently air
cavities, are often arranged in systems of parallel lines inter-
secting at different angles and occasionally there appears a
tendency to fracture along these lines, although it is hot suf-
ficiently pronounced to be called even poor cleavage. The
sections are completely isotropic in all positions and the
erystal system is therefore isometric. The melts are frequently
colored especially in shades of yellow or brown, the color
being probably due to contamination with platinum from the
crucibles in which the melts were made. The luster is vitreous
and the fracture conchoidal and often interrupted. The hard-
ness is about 5. The refractive index, measured on the total
refractometer, was found to be nxy,=1°608+:'002. The refrac-
tive indices of cr ystals from preparations slightly different in
composition from the 5CaO.3.Al,0, compound were measured
with the following results:
©2045. Al 028725). Nye 1°61 +1:003
CaO 49, Al 0, CALI CAL Bin N= I-61 b-=008
G50 50 ALO! 401.002 10 Nx, = 1°611 £003
None of these een were good, and in view of the
lack of homogeneity of preparations adjacent to the 5CaO.3.A]1,O,
compound in chemical composition, it is evident that solid
solution in this compound is not pronounced, but is, in fact,
extremely limited if present at all.
The refractive index ot the glass of the composition of this
compound is about 1°662; it is interesting to note that in this
compound crystallization means molecular rarefaction and not
molecular condensation, which is usually the case.
The unstable 5Ca0. 3AI,O, compound : CaO 47°78, Al,O,
52°22.—The crystallogr aphic development i is much less favor-
able for optical examination than that of other members of the
lime-alumina series. The very fact of its unstable character
precludes crystal growth for a long period of time under any
but very special conditions, and as a result the material avail-
able for investigation is finely crystalline and usually intricately
intergrown, either as radial spherulites or in aggregates of over-
lapping and often roughly parallel fibers. The optic properties
which can be obtained with such material are few and less
accurate than those from well-developed crystals. The crystal
habit is fibrous to prismatic; cleavage if present is parallel
with fiber direction but not perfect. The luster is vitreous and
the color usually green and due possibly to slight admixture of
platinum from the crucible. The hardness is about 5. The
refractive indices were measured by the immersion method and
found to be a=1:687+ 002, y=1'692+:002. The birefringence
318. Shepherd, Rankin, Wright—Binary Systems of
is not strong and only rarely were interference colors as high
as yellow red of the first order observed, and even then the |
color appeared slightly abnormal, due evidently to the effect of
overlapping fibers. The optic axial angle is large and the
optical character apparently negative, but not easy to deter-
mine satisfactorily because of the aggregate effect of superposed
fibers. The plane of the optic axes is parallel with the elonga-
tion of the fibers. The fibers show parallel extinction with the
ellipsoidal axis c parallel with the direction of elongation.
Some of the more deeply colored grains are pleochroie with
a=blue green, c=olive green. Absorption a> c.
These properties indicate that this compound is probably
orthorhombic im erystal system. Compared with the other
members of the series, its chief characteristics are the refraé-
tive indices about 1°69, weak birefringence and tendency to
fibrous development. :
Evidence of solid solution of other compounds in this form
was looked for but was not decisive. Ina preparation con-
taining 50 per cent Al,O, the unstable form was observed and
there appeared to have slightly higher refractive indices, but
the differences were only in the third decimal place and practi-
eally within the errors of observation.
The CaO.Al,O, compound: CaO 35-44, Al,O, 6456.—No |
single crystals of this compound were obtained and the deter-
mination of the crystal system rests entirely on the optical
data. In one preparation of this composition from the iridium
furnace elongated needles and prisms were observed, but on
examination were found to be not single crystals but intricately
twinned individuals with only indications of poorly developed
crystal faces.
Twinning is a characteristic feature of this compound and
is especially noticeable on sections nearly normal to the acute
bisectrix. Such sections are intricately divided into a hex-
agonal meshwork of interlocking sextants which extinguish
in different positions. On such sextants the plane of the optic
axes was found to be usually normal to an edge. On plates
cut at an angle with the acute bisectrix, polysynthetic twimning
lamelize were often observed and in aspect were not unlike
plagioclase lamelle. The general development of the mate-
rial from the crystallized melts is prismatic with a tendency
toward fibrous character. Oleavage is occasionally indicated
and is then parallel with the direction of elongation and appar-
ently prismatic or pinacoidal in character. The fibers extin-
guish often parallel with their elongation, the ellipsoidal axes
a being then parallel with the long direction; but in many
sections the extinction is not parallel with the prismatic axis
and makes large angles with the same.
“
Alumina with Silica, Lime and Magnesia. 319
- The crystalline aggregates are colorless and vitreous in luster.
The hardness is about 6°5. The refractive indices a and y
were determined on the Abbe total refractometer, while 8 was
measured by the immersion method. y=1°661+°002; B=1°654
+003; a=1°641+:002. The birefringence is fairly strong
and interference colors of the first to third orders are common.
The optic axial angle was measured by use of the double screw
micrometer ocular on. sections showing an optic axis in the
field of vision. Owing to the frequent twinning some dith-
culty was experienced in finding suitable sections and the
values obtained also varied slightly in consequence. Five
fairly satisfactory measurements were made and the aver-
age value 2V=36°+4° obtained. Dispersion of the optic
axes is very slight and ordinarily not noticeable. On one
section the relations seemed to be 2V,>2V,. Occasionally a
section with apparently smaller 2V than usual was observed,
almost uniaxial, but this was possibly due to the effect of over-
lapping twinning.
These data indicate that the crystal system of the compound
CaO.A],O, is either monoclinic or triclinic and probably the
former. Unfortunately, no well-developed crystals were
obtainable and a more definite statement in regard to the
symmetry relations is not possible.
The 3Ca0.5Al,O, compound: CaO 24°78, Al,O, 75°22.—No
separate crystals of this compound were obtained and the
evidence as to its crystal system, whether tetragonal or hex-
agonal, is not satisfactory. The grains are rounded and range
from 02 to (05"™ in diameter. Basal sections are usually with-
out definite outline, though occasionally there is a tendency
toward quadratic outline, and it is possible that the crystal
system is tetragonal. No distinct indications of cleavage were
observed. Rarely rhomb-shaped to square grains were noted
which extinguish parallel with the diagonals and may indicate
poor pyramidal cleavage, or if hexagonal, rhombohedral
cleavage, but such grains were rare, and if cleavage be pres-
-ent it is imperfect. The luster is vitreous and the hardness
about 6°5. The refractive indices were determined by the
immersion method: wo=1°617+:002; e=1°651+°002. Ona
section parallel with principal axis the birefringence was meas-
ured roughly under the microscope and the value y—a=:032
obtained. The birefringence is, therefore, fairly strong and
the interference colors, even in minute grains, are of the first
and second orders. In convergent polarized light a normal
uniaxial, optically positive interference figure was observed on
basal sections. ‘The interference cross is well marked and on
thicker sections the inner edge of the first colored interference
ring is visible on the margin of the microscope field. In
320 Shepherd, Rankin, Wright—Binary Systems of
some of the sections a shght opening of the interference cross
was observed as though the substance were biaxial with small
2K, but so many of the sections were pertectly uniaxial that there
is little doubt of the uniaxial character of the substance. This
compound is readily distinguished from the CaO.Al,O, com-
pound by its interference figure, optical character and constant
refractive index, #—1°617. On practically every basal section
thin threadlike inclusions of a higher refracting, weakly bire-
fracting to isotropic substance, were observed and althou oh small
in actual quantity they are nevertheless present and may y be free
A1,O, or the unstable 8CaO.5Al,O, compound. They are too
fine for satisfactor y identification by optical methods.
In several of the preparations the crystallographic habit
of the compound was entirely different from the small gran-
ular type. The individuals were elongated, lath-shaped and
intricately intergrown and resembled in aspect yCa,SiO, after
inversion from the 8-form.* The optic properties, refractive
indices, birefringence, uniaxial optical character, proved to
be identical with the normal 3Ca0.5A1],O, compound and the
peculiar appearance is due in fact to inversion from a high
unstable form, just as in the case of calcium orthosilicate.
The unstable 3CaO.5Al,O, compound: CaO 24°78, Al,O,
75°22.—This eompound was obtained only after consider- ,
able experimentation with preparations in the iridium furnace.
Its presence was surmised first from the difference in crystal-
lographic habit of different preparations of the optically
positive form of this composition. In no case was it obtained
in pure state but invariably showed more or less alteration to
the optically positive form, and could not therefore be used
for density determinations.
No erystals of this phase were obtained and the determina-
tion of its crystal system rests entirely on the optical evidence.
The crystalline melts are colorless and often porcelain-like in
appearance. Here and there minute cleavage faces of lath-
shaped individuals glisten in strong light. On the whole, the
melts were well crystallized, some of the grains under the
microscope measuring as much as ‘5™™ inlength. The crystals
are usually prismatic in habit and show under the microscope
fairly well-marked prismatic cleavage. Their luster is vitreous
and hardness about 5°5 to 6. The refractive indices were
measured by the immersion method y = 1°674 + :002, B=
1-671 + :002;a¢ = 1°662 + -002. A~ direct determination” or
-the birefringence was made and y—a found to be approximately
‘013. The interference colors in ordinary powder sections
rarely exceed the second order blue and are usually gray to
*This Journal (4), xxii, 296, 1906.
Alumina with Silica, Lime and Magnesia. 321
yellow of the first order. The optic axial angle was measured
by the double screw micrometer ocular 2V = 35° + 5°. This
value is the average of seven different measurements and part
of the large probable error is due to the strong axial dispersion,
which is pronounced with 2V, > 2V,. The attempt was
made to determine the angular amount of this dispersion, but
the axial figures observed were not sharp enough for precise
work and only the general statement can be made that
2V, is several degrees larger at least than 2E,. The optical
character is negative. The grains extinguish parallel with the
prismatic cleavage. The ellipsoidal axis a, and with it the
plane of the optic axis, is parallel with the direction of pris-
matic elongation of the crystals.
The alteration to the optically positive form is clearly marked
in the powder. It proceeds from the surface of the grains and
works toward the center along the cleavage cracks and occa-
sional transverse cracks, so that as it proceeds the original
substance is replaced. by a fine meshwork of the optically
positive form. The alteration is accompanied by a slight
expansion in volume, about 2 per cent Judging from the refrac-
tive indices, and this in turn tends to facilitate further change
by producing further cleavage cracks and causing the crystal
to break down entirely. The resulting product of change
resembles y-orthosilicate in appearance and this fact suggested
the existence of this probably unstable phase of the
3CaO.5AI,0O, compound.
The above optical data indicate that this compound is in all
probability orthorhombic in symmetry. Its chief character-
istics are refractive indices about 1°67, medium birefringence,
small negative optic axial angle with strong axial dispersion,
the plane of the optic axes and the ellipsoidal axis a lying
parallel with the prismatic cleavage direction of elongation.
Aluminum oxide: Artificial corundum.—This substance
melts at an exceedingly high temperature, and in the present
series of experiments no special attempt was made to procure
measurable crystals. The optic properties were determined on
a fine-grained preparation prepared by heating fine impalpable
precipitated alumina in the iridium furnace to about 2100°.
The crystal grains thus formed are less than -05"™ in diameter
and of rounded outline. No definite crystal outlines nor
cleavage cracks were observed. Air cavities and minute
bubbles are characteristic and abundant. The hardness is 9.
The refractive indices were determined by the immersion
method, o = 1°768 + -003, « = 1°760 + -003. The bire-
fringence was found to be roughly -009 on a small section
parallel with the principal axis.
322 Shepherd, Rankin, Wright—Binary Systems of
In convergent light a faint optically negative, uniaxial inter-
ference fioure was observed. In short, the optical charac-
teristics of artificial corundum were, so far as determined,
practically identical with those of the natural mineral.
Silicium oxvide.—In the paper on the lime-silica series,* the
thermal and optical behavior of silica at high temperatures
was described. Recent work on the silica problem, at low
temperatures, has shown it to be much more complicated
than was at first supposed. In fact several phases have now
been found to occur in that region which were not disclosed by
the first investigation. The problem as a whole is not simple and
has not yet been satisfactorily solved, so that in the following
paragraphs only a report of progress can be made. Apparently
six distinct phases occur: a-quartz, $-quartz, a-tridymite,
£-tridymite, a-cristobalite, and {- cristobalite. These will be
considered in the order named.
a-quartz, or simply quartz, is the ordinary quartz of mimeral-
ogists, and. requires no further mention. On heating to 575°
it passes into 8-quartz, which is also hexagonal! but trapezohedral-
hemihedral in its symmetry relations and in other respects
slightly different from a-quartz. The change at 575° is rever-
sible and is exceedingly sensitive to minute temperature varia-
tions, a rise or fall of 1/10° at the inversion temperature being
sufficient to cause the inversion. These relations have been
described in detail and the literature references given in a
recent paper in this Journal. +
Tridymite (a-tridymite) occurs in nature in flakes of hex-
agonal outline. It has been made artificially by several different
methods but in practically every case in the presence of a flux.
At ordinary temperatures tridymite is imtricately twinned,
biaxial and apparently orthorhombic in symmetry (pseudo-
hexagonal). On heating, the crystals become uniaxial at about
130°,§ and the complicated twinning disappears ; the expansion
coefficient also changes abruptly at this temperature. On cool-
ing the reverse process takes place slowly and the change is
therefore enantiotr opic. This inversion of a- to §-tridymite
occurs without evidence of great strain or fracturing of the
crystals and it is probable that the specific volumes of the two
phases are nearly equal. The fact that natural tridymite er ystals
are hexagonal with respect to outline and orthorhombic in optic
properties, while at 130° they invert to a truly hexagonal sub-
stance, indicates that in all probability such hexagonal plates
* Day, Shepherd and Wright, loc. cit:
+ Quartz as a Geologic Thermometer, this Journal (4), xxvii, 421-447, 1909.
t Literature references cited in Hintze, Mineralogie I, 1459-1462.
§ Mallard, Bull. Soc. Min., xiii, 169, 1890.
|| Le Chatelier, Compt. Rendus, cxi, 123, 1890.
Alumina with Silica, Lime and Magnesia. 323
were actually formed above 130°.—At ordinary temperatures
tridymite, having inverted in the solid state, is intricately
twinned and intergrown, and its optical examination is not as a
rule satisfactory, especially on artificial erystals. The birefring-
ence is weak and the average refractive Index about 1:477.*
Crystal aggregates formed out of pure melts of SiO, or from
SiO, glass or by inversion of quartz heated to a high tempera-
ture, show the above properties except that the refractive
index is slightly higher, about 1:484-+-:003 instead of 1:477.
In the description of the tridymite from the lime-silica series,
the writer noted this higher refractive index but was unable’
to account for it. Through the courtesy of Professor Lacroix
of Paris, however, to whom specimens of the artificial crystals
had been sent, this difference can now be explained. Pro-
fessor Lacroix, after examination of the material, pronounced it
to be in all probability cristobalite, and not tridymite, and sub-
sequent examinations here have confirmed Professor Lacroix’s
determinations. Cristobalite has been found in nature only
rarely, and then usually together with tridymite. Its crystals
are octahedral in habit, but, like tridymite, are intricately
twinned and very weakly birefracting, so that the optical
examination is not satisfactory. Its refractive index is shghtly
higher than that of tridymite, about 1:49.+ The optical
behavior of eristobalite was first studied by Mallard,t who
found that at about 175° the crystals became abruptly iso-
tropic, and remain so at higher temperatures. On cooling the
reverse process takes place, §-cristobalite changing back to
the a form abruptly, the minute birefracting patches flashing
up throughout the entire slide as the inversion temperature is
reached. The volume change on this inversion is apparently
very slight. The fact that this change is reversible and that
natural crystals of cristobalite are octahedral in habit indicates
that they were in all probability formed above 175°, the inver-
sion temperature.
In the irregular crystalline aggregates obtained in labora-
tory preparations, tridymite and cristobalite can best be dis-
tinguished by heating in the thermal microscope. At about
130° tridymite becomes uniaxial and remains so at higher
temperatures, while in cristobalite no change oceurs until
about 175°, when the interference colors disappear completely,
the material becoming isotropic and remaining so at higher
temperatures. The refractive index of tridymite (1°477) is
slightly lower than that of cristobalite (about 1°484), but the
difference is not great, and ordinarily would not, perhaps, be
relied on to distinguish the two in very fine powder.
* Mallard, Bull. Soc. Min., xiii, 169, 1890.
+ Gaubert, Bull. Soc. Min., xxvii, 244, 1904.
t Bull. Soc. Min., xiii, 175, 1890.
324 Shepherd, Rankin, Wright—Binary Systems of
On heating crystal aggregates obtained from the SiO, melts,
also from SiO, glass and from inverted quartz powder, it was
observed that at about 175°, or slightly higher, they become
isotropic and remained so at still higher temperatures. This
behavior proved them to be eristobalite and not tridymite, as
had been heretofore supposed. |
Several preliminary tests of the heat change involved in this
immersion have been made and found to be clearly marked.
The investigation of the stability relations between the crystal
quartz, tridymite and cristobalite has not yet been completed,
and need not therefore be discussed at this point.
Al,SiO,: Sillimanite ; Al,O, 62°85 per cent, SiO, 37-15
per cent.—This compound crystallizes from the melt with
great rapidity on cooling, and as a result the preparations
available for the optical work are in general too fine-grained
for accurate determination. The crystallites are fibrous and
lath-shaped in habit, and, like the natural mineral sillimanite,
are often in close parallel groups. The optical effect is, there-
fore, usually that of an aggregate rather than of a single indi-
vidual. End views of the fiber bundles show that each lath is
prismatic in shape with a prism angle of approximately 90°.
In the center of nearly every section a minute inclusion is
present, often in the shape of a cross, the arms of which are
parallel with the sides. In this respect the sections resemble
in a way the chiastolite variety of andalusite. The end sec-
tions are weakly birefracting and extinguish parallel with the
diagonals. The refractive indices, which were measured by
the immersion method, are noticeably lower than those of pure
natural sillimanite, a fact for which no explanation has yet
been found. a=1°638+-003; B=1:642+-003 ; y=1°653+:003.
Direct measurements of the birefringence were made and
averaged roughly y—a about -014, but they were not satisiac-
tory owing to the fibrous character of the material and con-
sequent lack of transparency for good thickness measurements.
For the same reason the optic axial angle could not be meas-
‘ured satisfactorily. Judging by its general appearance, 2H
lies between about 40° and 75°, but unfortunately it was not
possible to obtain a more definite value with the material at
hand. The optical character is positive, and the acute bisec-
trix c lies in the direction of elongation of the fibers. On one
preparation of the composition Al,O, 60, SiO, 40, the erystalliza-
tion was somewhat coarser, and there the optical axial angle
was measured with the double screw micrometer ocular and
the value 2V=45°+4° obtained. Dispersion of the optic
axes was not observed, and if present is slight. In this prepa-
ration well-marked pinacoidal cleavage was also observed
parallel with the plane of the optic axes. The same cleavage
is characteristic of natural sillimanite.
Alumina with Silica, Lime and Magnesia. 325
In every preparation of sillimanite examined, there was
present between the sillimanite fibers an isotropic substance of
much lower refractive index, about 1°530. This same sub-
tance appears in other preparations of the alumina-silica
series, and is probably glass, since its refractive index n, about
1°525-1°530, agrees with that of sillimanite glass obtained by
extremely rapid quenching of the melt from the iridium fur-
nace. Sillimanite crystallizes with great rapidity, but its
melting poit is high and probably in the iridium furnace
preparations, where comparatively rapid cooling goes on
throughout the region of rapid erystallization for this silicate,
not enough time was given for the entire melt to crystallize
out, and small threads of glass are included between the crys-
tallized fibers and laths. If the refractive indices be used as a
criterion, crystallization in sillimanite means high molecular
condensation, and, as a result, numerous air spaces and cavities
appear in the crystallized mass. ;
The presence of glass and minute elongated air cavities
tended to render the optical tests for homogeneity in prepara-
tions adjacent to the pure compound uncertain. No free
corundum was observed in the preparation SiO, 35, AJ,O, 65, but
it was readily detected in the preparation SiO, 30, Al,O, 70.
So far as the optical evidence goes, solid solution of Al,O, in
Al,SiO, may extend to the composition SiO, 35, Al,O, 65, but
not to Si0,380, Al,O,70. The refractive indices of the sil-
limanite fibers in the preparation SiO, 35, Al,O, 65, were practi-
cally identical with those of the pure compound, but measure-
ments of a high degree of accuracy were not possible, because
of the character of the material.
Magnesium Oxide: Artificial periclase.—Preparations of
this oxide were made both by crystallizing the pure melt in
the electric arc and also from fluxes of magnesium chloride and
silica. ‘The crystals from the latter were well developed and
octahedral in habit with occasional small cube faces. From
the melt they occur as rounded grains often irregular in shape
and without polyhedral outline in aggregated clusters and
masses. Cubic cleavage is well marked even on the grains and
was produced directly on the octahedral crystals. Octahedral
_ cleavage if present is not distinct. The crystals and grains are
colorless and perfectly isotropic with refractive index 1°734 -&
‘002, determined by immersion method. The hardness is
about 6, apparently slightly above 6, since the grains appeared
to scratch adularia very slightly. Solid solution in periclase
is not great if it occurs at all. Ina preparation MgO 90, CaO
10, free lime was present in the usual rounded grains, while
the refractive index of the periclase was practically unchanged.
Am. Journ Scit.—Fourts SERIES, VoL. XXVIII, No. 166.—Octossr, 1909.
22
326 Shepherd, Rankin, Wright— Binary Systems of
Mg0.Al,0,: Artificial spinel, MgO 38°32, Al.O, 7168.—
Crystals of this compound were obtained by direct erystalliza-
tion from the pure melt in the electric are furnace. The
resulting crystals were minute but sharply developed octahe-
drons, clear and transparent, colorless and splendent in luster.
In the aggregate they occur frequently with approximately
parallel orientation in rows and clusters, not unlike skeleton
sali crystals in appearance.—Evidence of twinning after the
usual spinel law was sought for but without decisive results,
chiefly because of the fineness of the material. Oleavage if
present is imperfect and not well marked in the powdered
material. The hardness is about 8. The refractive index,
nm = 1°723 + -002 (determined by immersion method), is slightly
higher than that of spinel ordinarily, although spinels of even
higher refractive index have been observed. Under the
microscope the grains and crystals are isotropic and without
abnormal interference phenomena.
Evidence of slight solid solution, both with alumina and
magnesia, was indicated by the slightly lower refractive index
of the spinel crystals from preparations adjacent to the true
compound in composition (Al,O, 75, MgO 25 and AI,O, 60,
MgO 40). Satisfactory tests for homogeneity of adjacent
preparations were, however, not possible because of the
presence of small quantities of a birefracting substance of
refractive index about 1°66 and medium birefringence, but too
fine for definite identification. This substance occurred in
different members of the alumina-magnesia series and together
with both periclase and spinel, and is therefore possibly due to
impurity from the carbon in which the preparations were
melted.
Solid solution over a long range in the above series does
not exist. This is evident not only from the thermal work
but also from the optical tests for homogeneity and the deter-
mination of the optical constants especially of refractive indices
of the components of preparations intermediate in composition
between the compounds. The refractive indices of the com-
pound 5Ca0.3A]1,O, appear slightly higher in preparations on
either side of the true compound, and this might be taken to
indicate very limited solid solution, but the observed differ-
ences are practically within the limit of possible observational
error, and too much stress cannot be placed on the evidence.
The same holds true for the optically positive compound
3CaO0.5A1,O,, and also the optically negative form of the same
composition, for which the refractive index y appeared very
slightly lower in the preparation CaO 25-78, AI,O, 74:22,
than in the true compound, but the difference was within
the possible error limit and the evidence is not definite. The
Alumina with Silica, Lime and Magnesia. 327
optically positive. uniaxial 30a0.5A1,0, compound appears
noticeably biaxial in certain sections, and this may have been
due to solid solution, but if so the extent of solid solution is
not great. The unstable 5Ca0.3A1,O, compound and also the
CaO.Al,O, compound showed slight variations in the optic
axial angle which might be ascribed to the effects of solid solu.
tion, but in such instances the quality of the material was not
favorable for decisive optical tests. Evidence of slight solid
solution of MgO and also Al,O, in spinel was indicated by
refractive index determinations on preparations adjacent to
spinel in composition.—CaO may also take up small amounts
of MgO in solid solution, so far as could be ascertained by the
microscopic examination.
The geologic significance of these binary serves.—In the
preceding pages the optic properties of the several different
compounds of the different series have been cited in detail and
this evidence, in turn, has been used in general presentation of
this problem in the first part of this paper. The bearing of such
data, however, on geologic work has not been mentioned, and
it may be of interest to outline in a few paragraphs the partic-
ular kinds and scope of evidence which the different methods,
chemical, physical and optical, furnish in a problem like the
present one, which in turn is only a detail of still larger prob-
lems whose ultimate solution will be of fundamental importance
in the consideration of questions of rock and ore genesis and
allied phases of geologic inquiry.
In the general attack upon complex problems of this nature,
experience has shown that exact and definite data along three
distinct lines of evidence, chemical, thermal, and optical, are
necessary and usually adequate for their satisfactory solution.
No one of these three lines is of itself sufficient for the
complete solution of the problem, nor yet are they entirely
independent of each other. Although supplementary to a
certain extent, they overlap in their spheres of application, so
that the results obtained by one method can be and usually are
confirmed by those of a second, thus strengthening the foun-
dation of fact on which subsequent reasoning is based.—By
careful chemical work the purity of the preparations is insured ;
by thermal measurements the relative energy content of the
different preparations at different temperatures is investigated ;
while by optical methods the number of compounds in a given
preparation is determined (mineral composition), their optical
constants ascertained and their special relation to each other
recognized (texture).—To present more clearly the scope of
these three fundamental lines of evidence which are essential
for the solution of problems of this type, it will be well to
328 Shepherd, Rankin, Wright—Binary Systems of
consider each separately first, and then to indicate briefly
wherein they overlap and are mutually confirmatory.
Chemical data.—Modern research has shown that as a rule’
rock minerals are not single, simple compounds but complex
mix-crystals containing various other mineral compounds in
solid solution. ‘The investigation of such minerals and their
relations in rocks can only be satisfactorily carried on, there-
fore, after the characteristics of the simple compounds have
been ascertained, as well as the extent and the effect of the
by-mixture. In the general investigation of problems of such
wide scope it is necessary to begin with the simplest condi-
tions, and after these have been thoroughly mastered, to work
up to the more complex. From a physico-chemical standpoint,
rocks are as a rule complex systems, too complex in fact to be
treated satisfactorily until the simple integral systems of which
they are made up have been studied in detail. The present
lime-alumina series is only one of a number of two-component
systems which mark the limits of larger three-component
systems, and these in turn lead to still larger systems. Such
systems eventually become exceedingly complex, and the only
hope the observer has of mastering them is to begin with the
simplest cases first and then with the experience thus gained
to proceed step. by step to the more complex. The simplest
systems are the two-component systems, as the lime-alumina
series, and the chief function of the chemical work is to make
up preparations of definite composition and to guarantee their
purity throughout the investigation. Natural rock minerals
are almost never rigidly pure, in the sense of definite and
invariable chemical composition, and yet their investigation
from the standpoint of laboratory synthesis requires that at first
only chemically pure preparations of definite composition be
taken, and the properties of these determined accurately ; later
the actual minerals can be reproduced artificially and the effect
of solid solution of different substances in different proportions
can be studied and definite information obtained. Impurities
in solid solution tend only to veil the true relations of the
compound itself, and for the observer to allow such a variable
factor as impurity into the investigation at the very outset
would operate not oniy to increase the difficulties but also to
decrease the clean-cut aspect of the problem and the laws
underlying it.
Other data which are of a physico-chemical nature, such as
questions of relative solubility, concentration and the like, may
properly be considered in a later paragraph.
Thermal data.—The object of experimentation along these
lines is not only to reproduce rock-making minerals artificially,
but especially to study the conditions of their formation and the
Alumina with Silica, Lime and Magnesia. 329
temperature and pressure ranges over which they are stable.
From such data general laws of equilibrium can be deduced and
tested and then applied directly to the rocks themselves, which
in effect are the end-products of physico-chemical systems. In
the case of igneous and metamorphic rocks we have to deal
with chemical systems that have been subjected to certain
physical conditions which, in turn, have left their imprint or
seal on the end-product or rock now accessible to the geologist.
It is the task of the geologist to decipher this seal as he finds it
expressed in terms of mineral composition and texture, and
from it to infer the conditions of original formation. The
actual processes of formation have not been and in general
cannot be witnessed by him, and he must base his conclusions
on the existing evidence, weighed im the light of his own
experience. Such evidence is in part geologic, but in no small
degree experimental, and the more evidence of an experi-
mental nature there is at hand, the more confident is he of his
conclusions. Exact thermal data especially are lacking, but
are of fundamental significance, since they indicate limits at
which the energy content of the system changes abruptly ;
any change of this kind, such as the melting and inversion tem-
peratures of compounds, or eutectic temperatures of mixtures, is
most important, since it is the outward expression of a shift of
the equilibrium of the system, as a result of which profound
changes may occur. What before was stable may become
unstable, and vice versa; a rearrangement of forces accom-
panies the change in energy content and new stability relations
are at once established.
Under normal conditions, therefore, thermal measurements
are adapted to indicate the relative energy content of any
preparation at different temperatures. But by so doing they
indicate the presence of different compounds in a series and
establish temperature ranges over which these compounds and
mixtures of the same are stable.
Optical data.—The microscopic examination of the prepara-
tions, at ordinary room temperatures and after the changes
have taken place, does not of itself directly prove an energy
change in the system. In the thermal microscope such changes
ean be followed in their effect on the optical properties (melt-
ing down of crystal plates, abrupt changes in birefringence,
optic axial angle, and the lke), but such evidence is used
ordinarily only to confirm the purely thermal data. The pur-
pose of the microscopic investigation is primarily to determine
the compounds present in any preparation (composition, with
special reference to homogeneity and crystallization), to study
the relation of the different components to each other (texture)
and to establish by measurement the degree of departure of
330 Shepherd, Rankin, Wright—Binary Systems of
natural minerals with their varying admixtures, from the chemi-
cally pure ultimate types. By the microscopic examination of
preparations of different composition in a given series, the
number of compounds in the series can be ascertained, the dif-
ferent phases in which any given compound appears, and also
the extent to which any particular compound takes up an
adjacent compound in solid solution. The exact determination
of the optic constants of the different members of the series
furnishes, morever, data which permit any one of them to be
recognized, even in the presence of others. From a textural
standpoint, the formation of eutectics should give rise to
special textures, and in some instances it has been observed to
do so, but as a rule crystallization in silicates at high tempera-
tures does not proceed with suflieient regularity to produce
clearly defined textures, and in most instances differences
between the crystals first to form (phenocrysts) and the por-
tions last to crystallize out (groundmass, eutectic), are not well
marked and the attention of the observer is directed chiefly to
the crystal development of the individual’ crystals themselves.
This condition, together with the fact that the preparations are
usually examined in the powder form, tends greatly to reduce
the value and usefulness of textural evidence in the micro-
scopic investigation of such preparations.
The optic properties which are made use of in the micro-
scopic examination of artifical products are the usual ones
employed in mineral determinations in rock sections, and
would require no comment at this point were it not for the
fact that artificial preparations are usually much finer-grained
than rock sections, and that in addition it is necessary to know
the degree of accuracy of all measurements on such products.
This has led the writer to make practical tests of available
microscopic methods to establish their accuracy and adaptabil-
ity to the new conditions found in artificial melts. In the
course of the general investigation, several new methods were
devised with special reference to the new requirements and
have proved satisfactory. At the present time, the following
methods and optic properties have been found most serviceable
in the study of artificial preparations.
(1) Refractive indices.—In powder preparations the refrac-
tive indices are most readily determined by the immersion
method (Schroeder van der Kolk)* in refractive liquids of
known refractive index. On favorable clear grains the refrac-
tive indices can be determined by this method on grains
measuring even less than -01"™ in diameter and with a prob-
* J. L. C. Schroeder van der Kolk, Zeitschr. f. wiss. Mikrosk., viii, 408,
1898; also F. E. Wright, T. M. P. M., xx, 239, 1900; this Journal (4),
xxii, 385, 1904 ; xxvii, 35, 1909.
Alumina with Silica, Lime and Magnesia. 331
able error of about +°002. The Becke line method can also
often be used to advantage with refractive liquids. The
refractive index of the liquids or mixtures of liquids used is
determined on the total refractometer.
(2) Birefringence.—In this measurement the thickness of
the plate is measured with the fine adjustment screw of the
microscope by focusing a high power objective first on the upper
surface of the plate or grain and then on the lower surface as
it appears through the plate or grain itself. The apparent
thickness thus obtained is then reduced to the true thickness
by multiplying by the refractive index of the substance
measured. The interference color is determined either with
the Babinet compensator, the calibrated quartz wedge or the
Michel-Levy interference-color chart. This is only an approx-
imate method, and the results may be in error 10 per cent or
more, but usually the percentage error is less and the numerical
error is confined to the third decimal place.
(3) Optic axial angles are measured most readily in the
powder section by means of the double screw micrometer
ocular.* On favorable sections ((025"™ and over in diameter),
the probable error of such measurements is about + 1° in case
both optic axes appear in the field of vision, and + 3° in case
only one optic axis is seen. [or such measurements the grains
should be immersed in a liquid of the refractive index 8 to
eliminate errors caused by refraction on the uneven surfaces
of the grains. In weakly birefracting substances and inter-
rupted sections the axial bars are less sharply defined and the
axial angle values obtained thereon are correspondingly less
accurate.
(4) Haxtinction angle.—By use of the bi-quartz wedge platet
the position of total extinction can be determined on a single
trial within + 10’ on favorable sections. The extinction angle
itself is the angle between a given crystallographic direction
and a particular optical direction on a particular crystal face,
and the accuracy with which it can be determined depends in
part on the quality of the crystallographic development of the
erystallite itself. Under favorable conditions of crystallo-
raphic development, extinction angles can be determined
within 10’ and less, dependent on the number of readings taken,
on crystals measuring only -02—-03"™" in length.
(5) Color, pleochroism and absorption can usually be deter-
mined on grains measuring ‘02™" and over, and in certain
instances on still smaller particles.
(6) Other properties, such as dispersion of the optic axes
and bisectrices, and the general correlation of optic and erystal-
lographic properties, can occasionally be accomplished on
* This Journal (4), xxiv, 317-369, 1907.
+ Ibid. (4), xxvi, 349-390, 1908.
332 Shepherd, Rankin, Wright—Binary Systems of
isolated grains ‘02—-03™" in diameter, although for ease of
manipulation and general accuracy larger grains and sections
are preferable. It may be stated as a general rule that most
of the optic properties can be determined with sufficient
accuracy on grains measuring °02—-05™™ in diameter, and certain
optical properties on still smaller particles.
The great advantage of examining a preparation in powder
form rather than in the thin section is two-fold: (1) by the use
of refractive liquids, the refractive indices can be determined
at once and traces of inhomogeneity In a compound appear
most clearly if it be immersed in a liquid of the same refrac-
tive index; (2) the individual grains in the powder are isolated
and can be rolled about in the liquid and examined along
different directions if necessary. These two conditions are
difficult to obtain in the thin section. The chief disadvantage
of the examination of preparations in the powder form is the
loss of texture. In the thin section, the texture or relation of °
the different crystallites to each other is much more clearly
marked than in the haphazard particles of a powder prepara-
tion.
As a general rule, the morphologic development of crystal-
lites from artificial melts is poor and crystals suitable for
goniometric measurement are very rarely obtained. The
crystal system of any compound has to be inferred, therefore,
from the optic and crystallographic properties obtained by the
microscopic investigation alone.
Briefly summarized, the optical investigation is adapted
primarily to ascertain the mineral composition of the prepara-
tions of any given series, while the thermal work serves chiefly
to establish the stability ranges of these compounds, both alone
and in the aggregate, at different temperatures throughout the
series. Other evidence—specific gravity determinations, crys-
tallographic features, chemical behavior, etc.—tends further to
supplement and to substantiate the thermal and optical data.
Evidence of this nature is im part chemical and part phys-
ical, and properly falls in the domain of physical chemistry,
for its interpretation—wherefore the extreme importance of
this science in the study of rock and ore formation.
Geologic data.—In the study of rocks their microscopic
examination -and bulk chemical analysis have heretofore
received the most attention, and in fact petrography, which
has primarily to do with rock description and classification, is
a result of this study. The general science of rocks, however,
demands not only rock description and classification, but also
inquires into their formation and genesis, and this fact postu-
lates thermal evidence. In the petrologic treatment of rocks,
exact thermal evidence is just as essential as precise optical
Alumina with Silica, Lime and Magnesia. 333
and chemical data, and this can only be supplied by experi-
ment, since the amount of exact field evidence along these
lines which has been obtained up to the present time is exceed-
ingly slight.
A rock has been defined as a geologically independent part
of the earth’s lithosphere. It owes its position to the action
of certain geologic forces and stands in causal relation to these.
These forces are in part physical and crystallographic and in
part chemical, and the rock as it appears to the geologist is the
resultant end-product of a certain chemical system acted upon
by the geologic forces; such forces, however, have not always
remained the same throughout the history of any given rock,
but have changed from time to time, either slowly or abruptly,
and each change has brought with it new conditions of equi-
librium in the erystallized mass, and possible consequent
readjustment of mineral composition and texture. Such
readjustment in texture and composition, however, is rarely
complete, and the imprints or scars’of each period of geologic
activity are often clearly marked in the rock and to the trained
eye serve to indicate its past history. The geologist has to
rely chiefly on field evidence in his interpretation of the history
of the earth, but such evidence is in large measure qualitative
and does not of itself yield exact data along certain lines,
particularly with. reference to rock genesis and the actual
character of subsequent transformations. This evidence is
best obtained by direct experiment, by studying the erystalli-
zation of definite chemical systems under definite and deter-
minable conditions of pressure and temperature. The difficul-
ties of complicated texture and composition will undoubtedly
be much diminished when the simpler chemical systems have
been experimented upon and their behavior under different
conditions studied. The technical difficulties in such problems
are formidable, but once overcome in the simpler systems,
they are mastered for all.
Geophysical Laboratory,
Carnegie Institution of Washington,
Washington, D. C., June, 1909.
334 White—Specific Heats of Silicates.and Platinum.
Arr. XX XIII.—Specific Heats of Silicates and Platinum ;*
by Watter P. Wuaurre.
Tue thermal properties of the silicates present several points
of special interest. First is the value of the data in geological
calculations; second, the light likely to be thrown on the
nature of matter in general by researches through the long
range of temperatures within which silicates are stable; and
third, the opportunity offered of comparing the properties of
the same substance in different physical states, for silica and
many of its compounds, on account of their great sluggishness
of transformation, can be carried over the same wide temper-
ature range in the amorphous ( vitreous ) condition and in one
or more different crystalline modifications. The present paper
describes the beginnings of an investigation in this field upon
the subject of specific heats. The present results are prelimi-
nary, covering but a small portion of the field and presenting
values possibly differmg by a few tenths of a per cent from
those likely to be finally reached. Yet as practically no data
whatever are now available through much of the region
covered, and as the general properties of silicates are shown
by a few members of the group, this preliminary publication
has seemed worth making at the present time.
The method adopted as the standard is that in which the
heated body is dropped from a furnace into a calorimeter.
This, the oldest and most familiar method, seems also the most
accurate, since the more delicate measurements are carried out at
ordinary temperatures. Indeed, the single temperature deter-
mination necessary in the furnace is a source of greater error
than all the rest of the process put together. The difficulty of
operating a calorimeter near a furnace and of transferring the
often white hot body into the water without thermal loss has
often been counted very great, and its seriousness has been
the subject of dispute among workers in this field. In the
present work, it was found relatively easy to make all errors
from this source certainly less, and probably very much less,
than those arising from the lack of uniformity in the furnace
temperature.
The experimental process naturally divides itself into three
parts, the heating of the silicate, the transference to the cal-
orimeter, and the measurement of the quantity of heat.
1. Furnace temperature.—The one great difficulty of high
temperature measurements, that of obtaining uniformity of
* Preliminary notices of this work have appeared in the Phys. Rev., xxvi,
536, 1908, and xxviii, 461, 1909.
White—Specific Heats of Silicates and Platinum. 335
temperature throughout the working chamber of the furnace,
has thus far remained the chief difficulty in the present work.
The working chamber of an electric resistance furnace is
cylindrical. The heat is produced in the sides and escapes
more or less through the ends, which are thus at a considerably
lower temperature. Any body within will necessarily have an
uneven temperature whose exact distribution depends on the
body, as well as upon the furnace. The correction of this
uneven temperature is somewhat troublesome, but will of
course be essential as high temperature measurements become
more exact.* Indeed, the comparative indifference to the
question of furnace temperature distribution shown by the
authors of much work already done is rather surprising. In
the present case the furnace first used, whose working chamber
was 16™ high by 6™ wide, showed by actual measurement
differences of about 20° between different parts of the charge.
The corresponding error, that is, the difference between the
average temperature of the charge and that of the ther-
moelement which enters and measures it, would be under
10°, or one per cent, at 1000°. It very soon appeared that
the precision attained in the other measurements was such as
to justify an attempt to diminish this furnace irregularity
and a new furnace was constructed 20 by 4:5 in internal
dimensions, in which partitions above and below the charge
partially shut off the cooling effect of the ends. These
partitions were of fire-clay 5"™ thick covered with platinum
on the side toward the charge to give a reflecting surface.
Thermoelectric measurements outside the crucible contain-
ing the charge now showed a maximum difference of 15°
at 500° and of 6° at 1500° with a maximum systematic error
at 500° of perhaps 0°5 per cent between the average tem-
perature of the charge and that of the thermoelement used to
measure it. The other sources of systematic error are small,
and the greatest accidental errors in the final results ( with two
or three exceptions, which cannot be definitely accounted for )
ranged from 0°5 per cent at the extreme to 0°2 percent at the
intermediate temperatures. These accidental errors are less
for platinum and for a charge of glass which was melted into
a single cake than for the other substances, which consisted of
separate lamps. From this it would appear that the accidental
errors are mainly connected with failure to hold the furnace
temperature steady for a sufficient time, and are not to be taken
as indicating a large systematic error. The present systematic
error then may fairly be inferred from the temperature dis-
*See, e. g., Some New Measurements with the Gas Thermometer, by
Arthur L. Day and J. K. Clement, this Journal, xxvi, 412, 1908. Several
other schemes for obtaining a very uniform high temperature are now
under way.
336 White—Specific Heats of Silicates and Platinum.
tribution in the furnace and from the magnitude of the
accidental errors, and on that basis is almost certainly under 1
per cent at the extreme and 0°5 per cent at the intermediate tem-
peratures, and these values may be even smaller later on.
2. The Drop.—Two features characterize the process of
dropping into the calorimeter and have rendered its results
very satisfactory. (1) The enclosing crucible is first tared as
to its thermal effect by dropping it alone, and the heat
quantity thus obtained is then subtracted from subsequent
determinations at the same temperature. This assumes that
practically all the heat loss in dropping comes from the eru-
cible alone, but as the time of fall is less than one-fourth of
a second, and the greatest total loss of heat is only 4:7 per cent
of that carried by the crucible, or 0°6 per cent of the total
quantity measured, this assumption seems justified. In
order to reduce, as far as possible, all variations in the heat
loss, the crucible, when dropped by itself, is loaded with
platinum so as to have about the same weight as at other times,
and hence to pass through the surface of the water at the same
speed. The specific heat of the platinum is so low that the
error in the correction for it is certain to be under 0-1 per cent.*
(2) In the second place, the operations of dropping are per-
formed as quickly as possible. his is accomplished as follows :
(See fig. 1.) The bottom of the furnace is first dropped by pull-
ing a latch (L), and falls into a box (B), which is hinged so as to
swing horizontally out of the line of fall. A rapid glance at the
furnace bottom tells whether it has fallen properly, that is, with-
out the crucible, and with everything else that should come.
The box is then swung aside, and as 1t moves it automatically
shuts off the heating current of the furnace, and passes 40
amperes or so through a fine platinum wire by which the
crucible is suspended,t allowing it to drop. The immediate
return of the swinging box cuts off direct radiation from the
furnace to the calorimeter. The whole operation requires
about a second and the error from doubling the time, which
has been several times measured, is negligible. Schemes for
moving calorimeter or furnace have often been tried by others
and were contemplated here when the present work was
planned. But the device just described, which amounts to
moving only a light wooden shield between the two, was tried
first for its simplicity, and soon proved to be altogether the
most reliable and effective, reducing the time to a minimum,
yet giving the observer a chance to prevent many accidents
* The error avoided by its use is probably no greater than this, but it
seemed best to substitute a measureable error for a more uncertain one.
¢ This method was adopted from J. A. Harker, Specific Heat of Iron at
High Temperatures, Phil. Mag., x, 430, 1905.
White—Specijic Heats of Silicates and Platinum. 337
which result from almost any entirely automatic device. The
water raised by the splash falls back into the calorimeter from
the walls of an extension tube which is immediately afterward
removed. The heat lost in this way, and from the few drops
Hrese
Je
Ue
Bes
Pzz) | |
N
Mes
INIZLZ CL
ZANYZZZ2Z aN
PA
N
N
y
x
. DIZ7ZWN
ero
IN GLEM Ls S
POUT
Fic. 1. Sectional view (somewhat simplified) of the furnace, swinging
shield (B) and calorimeter, about 1/7th natural size. A porcelain tube carry-
ing the thermoelement (7) enters the crucible fromabove. Pulling the latch
(ZL) drops the furnace bottom and lower partitions (P) into the box (B), which
at once swings aside and automatically shunts a heavy current through the
wires (marked +,—) supporting the crucible and drops the latter in the
(open) calorimeter below. The crucible comes to rest in the position indi-
cated by the dotted outline.
which occasionally escape altogether, is certainly negligible,
for in one set of measurements, when 40° or so of splash
water failed altogether of return to the calorimeter, the heat
3388 White—Specific Heats of Silicates and Platinum.
thus lost was under 0:2 per cent of that in the usual silicate
charge. The total resultant effect of this method of dropping
is to reduce all its errors to accidental ones, whose magnitude
can be gathered from the agreement of results. In a number
of test drops with a heat quantity one-fourth that subsequently
used, the variations were about 0°3 per cent. Assuming all
these to have resulted from the dropping (which is highly
improbable), this leaves for the resultant error from this cause
less than 0-1 per cent.
The Calorimeter.*—The distinguishing features of the eal-
orimeter were mainly determined by its use in connection
with the electric furnace. These are: (1) That the customary
water jacket around the calorimeter includes a water cover
and incloses it completely. This arrangement, however, is
much more than a mere protection against the furnace. It has
been independently adopted by several workers for deter-
minations at ordinary temperatures,t and seems likely to
‘become a customary feature in calorimetry of the greatest pre-
cision. The particular form of jacket cover is new, and
appears to have some advantages in simplicity and convenience.
It is shown in fig. 1. A single body of water is used, the por-
tion in the cover being held up by the atmospheric pressure
upon the free surface of the water in the jacket. It is made to
circulate back and forth between the two by the action of a single
propeller. The stirring and circulation are not in the least
disturbed when the cover is swung aside to expose the calori-
meter. (2) A second distinguishing feature is the use of a
very accurate and sensitive multiple thermoelement as a calori-
metric themometer. This choice was originally dictated by the
tact that the furnace temperature measurement requires a ther-
moelement, therefore a potentiometer, and so it was more con-
venient to adapt the other temperature measurements to that
instrument. The combination of thermoelement and potenti-
ometer, however, has also proved advantageous in other ways.
In addition to the general advantages of electrical over mer-
cury thermometers and an accuracy about as great as that of
the best resistance thermometers yet devised, it has the
important advantage of readily permitting practically simulta-
neous measurements of a number of different temperatures.
Its use enabled the determinations to be easily made by a
single observer. (3) A third feature of the calorimeter is the
attempt to avoid entirely bodies of uncertain temperature,
chief of which ordinarily is the cover, separated by some
* Preliminary notes on this calorimeter and the methods used with it have
been given in Phys. Rev., xxv, 137, 1907; xxviii, 462, 1909.
+ E. Bose and A. Miuller., Gott. Nachr. 1906, 278; Beibl., xxxi, 482, 1907.
Theodore W. Richards, 8S. J. Henderson and H. L. Frevert, Proc. Amer.
Acad., xlii, 575, 1907; Zeitschr. phys. Chem., lix, 535, 1907.
White—Specific Heats of Silicates and Platinum. 3839
distance from the water. The cover used here is in the form
of a floating cup, and therefore had always the same temper-
ature as the rest of the calorimeter surface. (4) An inno-
vation has been made in calorimeter practice by working with
temperature intervals much greater than usually employed (in
one case, 23°, which is more than ten times the ordinary rise ).
This method increases the accuracy by diminishing the relative
valne of thermometric and other important errors. It requires
an allowance for the variation in the cooling rate over the wide
temperature intervals (deviation from Newton’s law ), but the
difficulties of this correction have proved absolutely insig-
nificant—tar less than had been anticipated.*
No work has yet been done with this calorimeter of suffi-
cient precision in other respects to fully test its accuracy.
From the agreement (0-1 of 1 per cent) obtained in determina-
tions of a heat quantity no more than one-sixth to one-
twentieth of that usually employed, the accuracy is seen to be
more than sufficient for all requirements of the present work.
The Specific Heats.—Specitic heat, like density and con-
ductivity, is a property varying with the temperature. Unlike
them, it is almost never determined directly for any particular
temperature. For the specific heat is, essentially, the heat
given out by a body in falling through a given temperature
interval divided by the interval. To give the true specific
heat at any temperature, this interval should be infinitesimal;
in practice, it is necessarily finite and often very large. The
result obtained is the mean specific heat for the interval, from
which the different true values occurring within the interval
smay vary widely. Ifa single interval only is employed, the
relation between the mean and the true heat can not be deter-
mined; hence, unfortunately, most published values are
of the mean heat only and give merely approximations to the
true heats. If data are available for several different intervals
all values of the true specific heat within them can generally
be obtained. Three computations were required in the present
work: (1) The mean heats were corrected down to zero, (2)
to even temperatures at the upper end, and (8) the true
specific heats were then derived from these corrected mean
heats. The first correction was performed as follows: Let
M, be the observed mean heat, found between the tempera-
tures, 7, and @,.. Let m, be the mean heat from 0 to @,, M, from
0 to @,,and M, from 0 to the even upper temperature @,,.
Equating total heats, M,?, = M, (@,-0,) + m, 9,
whence M, = M, + (m, — M,) 7 (1)
*See Phys. Rev., xxviii, 462, 1909.
340 White—Specific Heats of Silicates and Platinum.
Before this equation can be applied, m, must .be determined,
which can be done with entirely sufficient accuracy as follows :
If #(@) is the total heat required to raise the body from 0
to 8,
AM) is the mean heat from 0 to 0, and Lo (2)
is the observed mean heat, M,. If now @, = 0, this reduces to
0
a) that is, to m,. If, therefore, the observed mean heats
are plotted and the curve extrapolated to 0, the value of m,
is obtained.*
For reducing the upper limit to a round number, an equation
like (1) is not so easily applied, since the quantity correspond-
ing to m, is here unknown, but if the interval of reduction is
small, as it always was in the present work, it is possible to
write
MS Me A Meander — a (0,-0,)
by means of which the correction is easily made, taking
from the tangent to the plotted curve.
The relation of the true to the mean heat may be expressed
in two ways: (1) If the true heat is given by the polynomial
A+B@+C@+... the total heat from 0 to any temperature
is the integral of this, or A90+2B0?+3C 6 +... and the
mean heatis A +2B@0+3C6 +...+ If, then, the mean heat
is expressed as a polynomial, the method of getting the true
heat is obvious. (2) Unfortunately, the specific heat curves
thus far obtained are not well represented even by polynomials*
with four constants, hence the following mothod, which may
be applied graphically, was actually used. If the total heat
is f (@) and the mean heat ay) f' (@) is the true specific heat.
But if the mean heat is differentiated and then multiplied by
(
6, giving f (6)- sh © and to this is added the value of the
* The approximations here made are easily seen, but as just stated, were
not practically important in the present work. A more rigorous correction
can be obtained by expressing the mean heat as a polynomial, that is, as
equal to
A + B(@, — 0:) + C (0.2 + 0; 62 + 4,°) +... (8)
and thus determining A, B, C,
A+B64,+C6.2+... (4)
is then the corrected mean heat. Both these expressions of course involve
the error incidental to representing almost any actual physical function
mathematically, but their difference will give very accurately the small
correction required to reduce the lower limit to 0. Or (4) can be used to
give m, and (1) then applied.
+ Behn has already given a similar treatment, Drud. Ann., i, 268, 1900.
White—Specific Heats of Silicates and Platinum. 341
mean heat, the result is 7’ (@) or the true heat. Hence if the
mean heats are plotted and a curve drawn through them (fig. 2)
Bie. 2.
Sprciric Hat.
TEMPERATURE.
Fie. 2. Diagram illustrating graphic determination of true specific heat.
and the tangent to any point m of the curve is produced to the
y axis, say at g, the projection, pg, of the tangent on this axis,
added to the mean heat, gives the true heat for the tempera-
ture of n.
Fixperimental results.—Most of the results so far obtained
are given in Tables 1 and 2, and graphically in figures 3 and 4.
The values for orthoclase and the glass of the correspond-
ing composition* were obtained with the wide furnace first
used. Determinations of wollastonite and pseudo-wollastonite
with this furnace ran about one per cent above those obtained
later, hence the orthoclase and “orthoclase glass” results have
been arbitrarily lowered two-thirds of a percent. The platinum
determinations were also made in this earlier furnace, but have
not been altered, as the good thermal conductivity of the
platinum probably reduced the systematic error considerably.
Of course, these results are not quite as certain as the later
ones. Otherwise, the results from 700° to 1300° probably
contain no error exceeding 0°5 per cent. This is, of course,
merely given as the result of careful consideration of all
sources of error. Obviously, positive statements as to system-
* Made by melting the orthoclase, which does not crystallize on cooling.
See Day and Allen, Publication No. 31, Carnegie Institution of Washington,
p. 00, 1904; this Journal, (4), xix, 120, 1905.
Am. Jour. Sci.—Fourts Series, Vou. XXVIII, No. 166.—OcropEr, 1909.
>
23
342
TABLE [.
White—Specific Heats of Silicates and Platinum.
Mean Specific Heats from Zero, of Platinum, Pseudo-wollastonite,
Wollastonite, Orthoclase, ’ Diopside, Quartz, Orthoclase
Glass, and a Soft Tubing Glass.
| Or.
Upper P- ; Soft
Temperature tira Os | ye Qu. Glass| Glass
LOO MEE eee wien | cee (888) eee) L919 elas | eee ee
aces weve |) °18383. °) 2252) 1905 1-850 2) ee eee ae
eo eA See eee Zoo) LOO 5 eee ime Tea
HOO eae aes 03348 | -2159 | [-2180] | -2248 | -2310 | 2372 | -2291 | -24000
03859 | °2169 | -2169 | 2246 | °2308 | 2368 | :2304) -24077
Coe |e RLG8 ee ee eo ee ere
28, ae coe nee ae ean "2410 +
HOSS er ere 034235) - 222) 228604) 22 e420ni 2547 ]* ---- | °2646
03428 | ..- 2289 | .2-. | °2422.|) 2559 *) See ee Gag
Sapbearah | Vm ae slog e220) 206 aan sae
SOO eee aol iS rae Siete! CAO 1 Meee ee lene "PAGO A i aaa
fee aa Bee we SO (Olea 20k =. | SRA eee
90022 eee 08515 | 222 | 12804 30 2227] “2499 | -2507 eee ee et
03014 |... |°°2808 | = 2. ,| +2488 152094 see ee ap
ae i Secs @AOos| casas ai i ee
LOO eye ee Se 03578 | °2380 [2423] Mea MielieisctaeS) |. ae
03578 | °2880 | °2404 | -2505 | -2562 | °2643 *| -2588 | -2907
----- | 2875 | °2404 | °2518 | 2564 | -2646 *| -2591 | -2909
eee eh eee 24 Oot alee |
LSOOE Sete ees 03640 | 2422] ___- Mia [.2613 | Mperee es 0 Sake
03647 | 2416 | __- -7... |) 2096 os | ea ee
Si ae eee WEA. aon f ROOD ieee ee es
RS ee ae ae . ie week | Lo eed ieee
1o00 2. kas 03600") 9222 nee eas woe Oe Se ee eee
03682 eis hey. pet Se A ACW -22u) |\ t2006
uberis yee ae See Cae owe eee ---- | °8024
* Affected by the inversion at 579°.
TABLE II.
+ Heated by lead bath.
True Specific Heats of the Substances given in the preceding Table,
except Quartz.
Temperature! Pt. Viol, 2) Ee NV Olt Or: Di. Be af ok
DOO 22 Aoi "0356 "251 250 207 "262 "264 298
(00 eee 0368 "265 ee ai "272 “B24
S00E aes ee ante eens 212 Site 282 eee
SO Os eae aes 0380 “262 te “281 2 “340
LOO? Zea ‘0390 261 “209 279 "286 297 "330
OOH Edin ae | 0400 nae "207 ee 278 ae 338
LSS ao ese “0407 1 she BS ae sae "332
343
White—Specijic Heats of Silicates and Platinum.
“WUNUT4R[G —3g ‘“zj1enh—- *o71U0ysSeI[O M -Opnosg — g ‘eyUOFSVTIO AA = MA ‘optsdorp=—iqg ‘sseLH esepooqyIQ= [4H “10
‘esepPOOJAIQ—=1Q ‘Sse[H WOS=[H "OOTT 32 qd pue M JO souUsLEzIpP oy} 03 [enbe 4ynoqge sit 1o119 UWMUILXeO ot,
‘| @1av], 40 SLVAP OlaIOGdS NVA
~
Sisal eee eee Ree 6
SHAE pt pp
AS Gaaae aa eee eae ees
ENTS ES ee ee ee ees Pes Ras:
co Nea VANES BE ee Be eee ae ae
pee bae eS ise Sei eA is
: AAG
: :
=
G
2
oe
Wi
a
a
ZB
ate
ie
"g
_
.
as
cc
a
#
is
a
a
2
4
"
ioe
us
fa
1100°
900°
700°
SiS ie mp
Se eae SNS Ree eee
SS ae NSN ae eee oe aera
[ES eS Es oN Ce a ee
SESE ER ES SSRs oe
WSs 9
st CO
CO GR Qr XR Se SUS IG GR SE GR SE TODAS GI GY = Oo. ©
500°
300°
eal cs
Ht} ft
0° 100°
‘SLVAEL OLALOMAS
TEMPERATURE IN DEGREES,
344. White—Specific Heats of Silicates and Platinum.
atic error can seldom be based on one series of determinations.
The results for quartz and platinum are several per cent lower
than values given in Landolt and Bornstein. Two values for
platinum at 600°, given by Plato, fall within half a per cent of
the curve here given.* I have found no published data for
the other substances as high as 500°.
Eighteen earlier determinations on wollastonite and pseudo-
wollastonite have been omitted as now worthless and to avoid
confusion. All the other observations are given, the rejected
ones being bracketed.
In order to establish as certainly as possible the small dif-
ference between wollastonite and pseudo-wollastonite, special
precautions were taken against any change in conditions
between the two sets of determinations. The wollastonite was
inverted to pseudo-wollastonite directly in the calorimetric
crucible, so that the same lumps, in the same positions, served
for both. As a check on possible systematic errors the pseudo-
wollastonite determinations were repeated with half charges,
showing very fair agreement.
The two values for soft glass at 500° first obtained seemed
suspiciously low, as they cause a distinct reversal of the curva-
ture. Two further determinations were therefore made in a
new furnace, where the crucible was surrounded above and at
the sides by a stirred bath of lead, and below by an electrically
heated plate, whose temperature was observed and regulated.
The results agreed to 0-1 per cent, and were only about 0°5 per
cent above the old ones. This indicates that the peculiarity in
the curve of this glass is really due to the substance itself, and
also tends to confirm the estimate above (p. 335) as to the
systematic error of the older observations at this temperature.
The accuracy of the true specific heats is less than that of
the mean heats, from which they are derived. This is because
the true heats are dependent on the differences of the others.
The inversion in quartz at 575° renders more numerous data
desirable before computing the true heat for it.
The mean specific heats of platinum and of diopside are
expressed by the following formulas :
Pte eee 03198+3°4 10-6
CaMgSi,O,.. 1779 +1°516 x 10-6—1-047 x 10-6 + 2°81 x 10-163
The agreement with the simple curve of platinum is as good
as the original data, but the formula is not recommended for
extrapolation. With diopside it amounts to only half a per
cent, and a curve with one less coefficient is nearly as good.
For the results at 100° the heating was done in a steam
bath.
*W. Plato, Erstarrungserscheinungen an anorganischen Salzen und
Salzgemischen. I, Zeitschr, phys. Chem., lv, 736, 1906.
White—Specific Heats of Silicates and Platinum. 345
Fie. 4.
2aneen sane
aro
np ae
“2 oe ae
Orthoclase ;
Platinum, ~
2 SS SS BSS SS
Soft Glass; Or
Pseudo-Wollastonite; Pt
Bs Ba Set
SeSRe\e
, aeons
J Cea
eee bp
oe ee
Bee r i,
| ease
BRE eee ar
JSS
See e ee i
a
Bees ah
Js oe seaee
mee se lls
BERGE:
ei ae a
pele kee Oca ae
eee ee eee
Megribas ds eam
et ea
es a
epee
900" 700% §$00° 11007:.-1800° . 1500°
TEMPERATURE IN DEGREES.
TruE Speciric Heats oF TABLE II.
Errors here may equal the difference between the Or and Di curves. Gl
Wollastonite; P
W=
Spreciric HEATs.
Diopside ;
“1000
Orthoclase Glass; Di
Gl=
On
‘0400
‘0300
346 Whete—Specific Heats of Silicates and Platinum.
Summary.
1. For determining the specific heats of silicates up to 1500°
C. the method of mixtures, in which the heated substance and
containing crucible are dropped from a furnace into a calori-
meter at room temperature, was selected as the most accurate.
2. The chief source of error is in the lack of uniformity in
the furnace temperature. This has been diminished in some
cases by the use of special forms of furnace.
3. The error introduced in the process of transferring from
the furnace to the calorimeter is negligible. An electrical
method of releasing the crucible greatly reduces the time
required, and preliminary determinations made with the con-
taining crucible alone eliminate what heat loss there is.
4, All temperatures, including that of the calorimeter, were
read by thermoelements. By this means rapidity and simplicity
of manipulation were secured.
5. The calorimeter was completely inclosed by its water
jacket. An unusually large temperature rise (sometimes 23°)
was successfully employed to increase accuracy.
6. Some simple ways of treating specific heats mathemati-
eally are given.
7. A consideration of the various sources of error indicates
for the mean specific heats a final accuracy of better than 0°5
per cent at most temperatures. The true specific heats,
derived from these, are less accurate.
Silicate specific heats show a considerable increase with
temperature up to 700°, followed by a tendency to diminish
at higher temperatures.
Geophysical Laboratory,
Carnegie Institution of Washington,
Washington, D. C., July 15, 1909.
Browning and Flint—Complexity of Tellurium. 3847
Art. XX XIV.—The Complexity of Tellurcum ; by Puri E.
Brownine and Witiiam Rk. Frint.
[Contributions from the Kent Chemical Laboratory, Yale Univ.—cciii. ]
AttTHoueH the consensus of opinion among chemists at
present seems to favor the homogeneity of tellurium* and an
atomic weight of 127°5, the recent work of Marckwald,} and
the last report of the International Committee on Atomic
Weightst seem to suggest that possibly the question of the
atomic weight at least has not been definitely settled.
The work described in this paper was suggested by the
observation that when water is added in large amount to a
solution of tellurium tetrachloride, this compound is hydro-
_ lyzed and the greater part of the tellurous acid is precipitated,
while some of the tellurium remains in solution however large
the amount of water present.
This observation was apparently first made by Berzeliuss
and later the method applied in a limited degree by Brauner|
and by Baker and Bennett{ to a process of fractionation.
It was further observed by us that the tellurium remaining
in solution after the treatment with water and filtermg may
be completely precipitated as the dioxide by heating to boil-
ing, treating first with ammonia and then with acetic acid in
faint excess, as described in a previous paper from this lab-
oratory.**
This procedure was applied with the result to be described,
in order to determine whether by means of it any light might
be obtained upon the possible complexity of tellurium.
About one hundred grams of crude tellurium, which had
been extracted by hydrochloric acid from electrolytic copper
residues, were subjected to a series of purification processes
such as have been commonly used for the purpose of prepar-
ing pure material. This crude preparation was first twice
fractionally precipitated by sulphur dioxide; then fused in
portions, in hydrogen, with potassium cyanide, extracted with
water and precipitated from solution by a current of air. It
was next reprecipitated, by sulphur dioxide, from hydrochloric
acid solution ; was fused in hydrogen, and finally distilled, in
a current of hydrogen, from porcelain boats in a porcelain
tube.
* Kéthner, Ann., xccexix, 1; Gutbier, Sitzungsber. phys-med. Soc. Erlan-
gen, xxxvii, 270; Lenher, J. Am. Chem. Soc., xxx, 387.
t Ber., x1, 4730. {J. Am. Chem. Soc., xxxi, 1.
§ Ann. Chim. Phys. (2), lviii, 113. || J. Chem. Soc., lv, 382.
4] Ibid., xci, 1849. ** This Journal, xxviii, 112.
348 Browning and Flint—Complexity of Tellurium.
Ninety-two grams of this pure product were converted to
tetrachloride and the solution, in as small amount of hydro-
chloric acid as possible, was diluted with four liters of boiling
distilled water, and cooled. The precipitate, seventy-six grams
of pure white, erystalline TeO,, was removed and the filtrate
was heated again to boiling, after which ammonia and then
acetic acid in the smallest possible excess were added. When
cold, thirty-eight grams of TeO, were obtained, more finely
crystalline than the preceding fraction, but also pure white.
The filtrate from this fraction contained no tellurium detecta-
ble by stannous chloride, and was consequently discarded.
These two fractions were next separately refractionated by
an exact repetition of the process above described, each frac-
tion secured being likewise refractionated, the three fraction-
ations thus providing eight fractions, of which the last, about
1:5 gram, was set aside. Fraction two was combined with
three, four with five, and six with seven, and each portion of
the material refractionated, as was also fraction one. From
this point on, the fractionation was carried out after the usual
plan of fractional crystallizations, intermediate fractions being ~
combined before retreatment, and those at the latter end of
the series being removed when small in amount (from one to
two grams). In this manner ten fractionations were per-
formed, as a result of which were secured about fifty-nime
grams of dioxide from the first, or water, end, and fifteen
grams from the last, or ammonia-acetic acid, end of the series.
Each of these portions was refractionated once, the water
fraction (50 grams) of the first being denominated alpha, and
the ammonia-acetic acid fraction (18 grams) of the latter, beta.
The alpha and beta fractions were lastly converted to basic
nitrate, the former by one and the latter by two erystalliza-
tions, according to the method described by Norris, Fay, and
Edgerly.* It is to be noted that.in the process of fractiona-
tion the material of each fraction had been crystallized out of
a large amount of distilled water.
The alpha and beta fractions were subjected to analysis by
three different methods: (1) the basic nitrate method ; (2) the
Gooch and Danner modification of Brauner’s permanganate
process ;+ and (3) the ammonia-acetic acid method previously
described.
(1) After bringing the basic nitrate to constant weight at
140° as recommended by Norris,} carefully weighed portions
were heated in platinum with a gradually increasing tempera-
ture for a period of five to six hours. The crucibles were con-
tained in porcelain radiators, a porcelain dish being supported
* Am. Chem. J., xxiii, 105. t+ This Journal, xliv, 301._
t J. Am. Chem. Soc., xxviii, 1675.
Browning and Flint—Complexity of Tellurium. 349
above each in an inverted position to distribute the heat more
evenly. Finally they were removed and ignited for a short
time at dull redness until the dioxide had fused to a glassy
condition. The weighings were conducted with properly
standardized weights, by the method of vibrations, and the
usual corrections were applied. The results are recorded in
Table I.
TaBsieE I,
2TeO., . HNO; Per cent
taken TeO, found TeO.
Alpha gram. gram. found
a 0°09575 0°07986 83°40
(2) 0°27354 0°22813 83°39
(3) 0°60237 0'50272 83°45
(4) 0°66288 — 0°55331 83°45
(5) 1°60542 1°338912 83°41
(6) 1°78565 1°48982 83°43
Beta
(1) 0:08473 0:07081 Ss co0n
(2) 0°23125 0°19256 83°63
(3) 0°87484 0°73306 83°79
(4) 0°39778 0°33232 83°56
(5 0°39479 0°33005 83°60
The mean percentage of dioxide in alpha (83:42 per cent)
gives an atomic weight of 126°53; that for beta (83°63 per
cent), 128°97. Itis thus apparent that the fractions are not
homogeneous with each other, since they had been crystallized
under precisely similar conditions, with due precautions to
secure constancy of composition in each case, and with exactly
similar treatment in the performance of the analyses.
(2) Analyses made by the permanganate process mentioned
above confirmed this difference. The material was dissolved
with two cubic centimeters of ten per cent potassium hydrox-
ide and the solution was acidified with sulphuric acid (1:1),
one cubic centimeter in excess, diluted to one hundred cubic
centimeters with water, and treated with an excess of perman-
ganate, oxalic acid being then added in excess. The mixture
was then warmed nearly to boiling and the excess of oxalic
acid determined by permanganate. The titrations were con-
ducted in porcelain dishes. The results follow in Table II.
Computation from the permanganate required for the oxida-
tion, in each case, gave a mean of 126°64 for alpha, and
128-77 for beta.
(3) A similar difference was again obtained by the ammonia-
acetic acid process already referred to. The basic nitrate was
dissolved with two cubic centimeters of hydrochloric acid, the
350 Browning and Flint— Complexity of Tellurium.
TasieE II.
2TeO, . TeO, TeOg Error TeO. TeO. —*iError
HNO; theory found on TeO, theory found on TeO,
erm. erm. erm. erm. erm. erm, grm.
Alpha (Te=126°5) (Te=127'5)
(1) 02537 021167 0-2119 +0°0003 0-218 0-2130) an ame
(2) 0:2508 0°2092 02093 +0:0001 0:2094 0:2106 +0°0012
(3) ~.0°2521 06-2103 0-2102 —0-0001 0:2105 0:2115) =aa;o0nn
(4) 0°2508 0:2092 0:2092 0:0000 0:2094 0:2105 +0-0011
(5) 0:2523 0-2104 0:2100 --0-0004 0:2107 02118 ==0-0006
(6) 0°2511 0:2094 .0-2092 —0-0002 0:2097 0°2105 -+0-0008
Beta (Te=128°9) (Te—127°5)
(1) 0°2504 0:2094 0:2095 +0:0001 0:2091 0:2077 —0-0014
(2) 0°2500 0:2090 0-2086 —0-0004 0-2087 0°2068 —0-0019
(3) 0°2505 02095 0:2095 0:0000 0-2092 02075 —0-0017
(4) 0°2505 0:2095 0-2095 0:0000 0:2092 0°2075 —0-0017
(5) 0°2504 0:2094 0:2100 +0°0006 0:2091 0:2083 —0-0008
(6) 0:2501 0°2091 0°2093 +0:0002 0:2088 0:2076 —0-0012
excess of acid removed as much as possible by careful evapor-
ation; the dilution was with two hundred cubic centimeters of
boiling distilled water, and the ammonia and acetic acid were
added from burettes. Filtration was performed after standing
over night. These results appear in Table IIL.
Tasie III,
TeO, TeO.
2TeO2, . HNO; theory found Error Per cent
germ. grm. germ, grm. TeO,
Alpha (Te=126°5)
(1) 0°2506 0°2090 0.2093 + 0°0008 83°51
(2) 0°2505 0°2089 0°2088 —0°0001 83°35
(3) 0°2529 0°2109 0°2108 —0:0001 83°35
(4) 0:2510 0°2094 0°2093 —0°0001 83°39
(5) 0°2507 0°2091 0°2091 0°0000 83°41
Beta (Te=128'9) .
(1) 0°2512 0°2101 0°2097 — 0:0004 83°48
(2) 0°2514 Op2 02 0°2108 +0°0001 83°65
(3) 0°2504 0°2094 0°2095 +0°0001 83°66
(4) 0°2507 0°2096 0°2095 —0:0001 83°57
(5) 0°2612 0°2101 0°2100 —0°0001 83°60
For alpha the mean percentage of dioxide is 83°40 per cent,
or Te=126°31; beta, 83°59 per cent, or Te—128°81.
Browning and Flint—Compleaity of Tellurium. 351
SUMMARY OF ANALYSES.
Process Alpha Beta
paste nitrates cos) wee ee 126°538 128°97
ermancanate ss). bie) L205... 12664 128307
Ammonia—acetic acid .__.-_- 126°31 128°81
(Meat ae Sie er i 126°49 128°85
It is seen that an atomic weight of 126°5 gives more satis-
factory results for alpha, while neither 126°5 nor 127°5 will
answer for beta.
Besides the experiments with the basic nitrate, just
described, the following experiments upon the dioxide are to be
noted. Two portions of tellurium dioxide from each fraction,
prepared by the ignition of the basic nitrates, were dissolved
in equal amounts of hydrochloric acid and treated with equal
amounts of boiling distilled water. The results given in
Table LV indicate different degrees of hydrolytic susceptibility
on the part of the tetrachloride prepared from these fractions.
Tas.eE IV.
TeO, taken TeO, found Percentage
grm. erm. precipitated
(1) 0'3000 0°2521 84°. %
(2) 0°3000 0°2602 86°7%
(3) 0°3000 0:2772 92°4%
(4) 0°3000 0°2806 93°5%
(1) and (2) were obtained from one fraction and (8) and (4)
from the other. (1) and (8) stood 22 hours before filtration,
(2) 26 hours, and (4) 18 hours.
A sample of tellurium dioxide obtained from the tellurium
tetrachloride by several hot water precipitations, according to
the procedure for the prepaxation of the alpha fraction, was
analyzed by the routanaandte process already described. The
results of the analysis of this specially prepared dioxide, as
given in Table V, show a close agreement with the analyses of
the basic nitrate prepared from the alpha fraction and recorded
in Table IT.
TABLE V.
TeO. taken TeQO2 found Error TeO, found Error
grm. erm. erm. erm. erm,
Te=126°5 Te=127'5
(1) 0°3066 0°3064 —0°0002 0°3076 +0°0010
(2) 0°2723 0°2719 —0°0004 0°2729 +0°0006
(3) 0°2229 0°2228 —0°0001 0°2243 +0°0014
(4) 02220 0°2220 00000 0°2235 +0°0015
852 Browning and Flint— Complexity of Tellurium. .
It consequently appears from the analyses by three different
methods that, in the end fractions obtained by fractional
hydrolysis of tellurium tetrachloride prepared from the care-
fully purified element, tellurium, seems to possess different
atomic weights. It is not claimed that these atomic weights —
have been determined with the utmost accuracy. ‘The two
fractions, however, have been in each ease treated exactly alike,
in a manner entirely competent to show at least approximately
whatever difference there might be. The preparations have
been carefully examined to discover the presence of any
impurities which might cause the difference, but no such
impurities have been found. At present, therefore, there
seems to be no explanation of the differences found other than
the complexity of the original substance. The investigations
just described are of necessity preliminary in character, and
the results of a more extended study of this fractionation
process, already begun by the latter of the two collaborators,
will be published as soon as practicable.
Palmer—Arizonite, Ferric Metatitanate. 353 ©
ART. XXXV.—Arizonite, Ferric Metatitanate ;* by CuasE
PALMER.
THE mineral, which is the subject of this paper, was found
on a mining claim belonging to Mr. A. G. Alm, about 25 miles
sontheast of the railroad station at Hackberry, Arizona. It
was received at the U. 8. Geological Survey by Mr. Frank L.
Hess, along with some gadolinite, of which the new mineral
was suspected to be a variety. The prevailing rock in the
locality of the find is granite. The new mineral occurs together
with typical gadolinite in a pegmatite dike. The gadolinite
gelatinizes with hydrochloric acid; has a specific gravity 4°28 ;
and a partial analysis shows that it contains:
ICR (OIO jes) est 24°41 per cent.
Mirae ‘earths. 22). 25502 2. 36°86
Werisearths <1... i BESO “ans :
memlian(iise® jee eat! BO ee se
Ferrous oxide (FeO) ._..---- dale Gees ota:
95 ‘83 6¢ 6¢
The new mineral occurs for the most part in. irregular
masses outwardly resembling the gadolinite with which it is
Bre. i:
associated. The weathered surfaces of the two minerals, how-
ever, differ, those of the new mineral being somewhat lighter,
in color inclining to grey. The vitreous appearance of fracture
surfaces of the gadolinite, moreover, 1s wanting in the new
mineral,
One specimen showed crystalline form. This was referred
to Dr. F. E. Wright, who has very kindly furnished the fol-
lowing preliminary cr -ystallographic description of the mineral :
“For the crystallographic examination and determination of
this mineral only one large and imperfectly formed erystal
was available (fig. 1, actual size, side view). Its faces were
rounded and unequally developed, and the crystal angles could
* Published by permission of the Director of the U. S. Geological Survey.
354 Palmer—Arizonite, Ferric Metatitanate.
be measured only approximately with a hand goniometer and
with a probable error of several degrees. So far as could be
determined from the forms present, the crystal system is prob-
ably monoclinic, in which case the plane of projection of fig.
1 is the plane of symmetry and the indices of the different
faces are a(001), 6(100), c(101), d(001), ¢(110) and (112).
Between these faces the following angles were measured:
Reflection.
OO: 100F—_ 125 eee fair 100): 001 .=* St? eee poor
O01 10! = MOG? Sea a 1003 £12-= (907 eae me
001 +)101. = MgO" +. poor 1102 10% 1h eee
OO) 26 60 ete ee a 110 2 2 =130 eee ac
NO Ores 1eOp— Ol cee eee eG 101: 001 = 10a “c
WOO STO SS 1SO" 2 oa. . eG 112: 101 = 124 See és
These values are not sufliciently accurate for a satisfactory
determination of the axial ratios, but it is approximately
O00 = N88 O87 8 Oa.
In the above calculation of the axial ratios, it is assumed
that the plane of projection in fig. 1 is a plane of symmetry.
No proot of this, however, was obtained, and it is possible that
the crystal system is triclinic or other system instead of mono-
clinic. Etch figures would be of service in deciding definitely
the system from the single crystal available.
“Under the microscope the larger particles of even fine
powder are opaque, but the very thin edges of minute slivers
are deep red in transmitted light, highly refracting (x > 1°84)
and of medium birefringence. Pleochroism is barely notice-
able in shades of deep red with absorption r>a. In the
thin section noticeable amounts, about 4 per cent or less even
in the freshest material, of a colorless to pale brownish yellow,
highly refracting substance, uniaxial and optically negative,
occurs and agrees in its optic properties with anatase.
‘“‘ A thin section made from an alteration product of the new
mineral shows that, as the alteration of the latter proceeds, the
amount of the anatase present increases until finally practi-
cally the entire substance is changed to a meshwork of fine
anatase aggregates. The luster becomes dull and lithoid, and
the color changes gradually from dark steel grey to a brown-
ish yellow. In the freshest material there is also present in
minute grains and laths a colorless, strongly refracting and
birefracting mineral which is not anatase but is negligible in
amount, and, so far as its effect on the chemical analysis of this
material is concerned may be disregarded.”
The mineral is decomposed completely by hot concentrated
sulphuric acid. The residue, insoluble in the sulphuric acid,
contained all of the silica and about one half of one per cent
Palmer—Arizonite, Ferric Metatitanate. 355
pure titanic oxide. The latter is apparently present in the
mineral in the free state. This view accords with Dr. Wright’s
observation that the mineral contains a small quantity of
anatase.
The following analytical results were obtained by decom-
posing the mineral with sulphuric acid:
ANALYSIS.
Per cent Ratio
PRI ORE IS «Jee 056“ «
Insoluble Poa oo eae once
(GreO eos Rs Be Ons Pins
Fe,0, Sees hea om SS8rsOus we 11
Soluble < IO ey ae ee OC OG nS nme oe a-O3
| H,O— LALO REN Ros pal bo ena ak
| H,O+110¢ ee Ae gs LOO Ss are’
100°12 (45 6¢
The close ratio of ferric oxide to titanic oxide, viz., 1 : 3°03,
indicates that the mineral is really ferric metatitanate,
Fe,O,.3TiO, or Fe,Ti,0,. Moreover, the crystallographic de
terminations strengthen the view that this titanate of iron can-
not be assigned to any known species, but is entirely new. I
propose to name it Arzzonite.
Arizonite is apparently without cleavage. The fracture is
subconchoidal. It is brittle, with hardness between 5 and 6,
specific gravity 4°25. Fresh fracture surfaces are dark steel
grey in color and metallic to submetallic in luster. Its streak
is brown. The mineral is opaque and is not magnetic. It is
partially decomposed by hydrochloric acid. The filtered solu-
tion, containing ferric chloride, responds readily to the oxida-
tion and reduction tests for titanium.
There appears to be no authentic prior record of the occur-
rence in nature of a simple ferric metatitanate (Fe,O,.3Ti0,).
The literature furnishes, however, a few examples of the exist-
ence of this form of titanic iron, either admixed or combined
with ferrous titanate (feO.TiO,), the usual form of natural
titanic iron.
Rammelsberg* recognized that a variety of iserine, described
by him as of uncertain crystallographic form, is a titanate of
ferrous and ferric oxides. Upon readjustment of the analyti-
cal data as cited by Rammelsberg, it appears that his mineral
consists essentially of 60 per cent ferrous titanate (FeO.Ti0O,),
ilmenite, and 40 per cent ferric titanate (Fe,O,.3Ti0,), arizonite.
Attention is also called to the low specific gravity of this iser-
ine, viz., 4°4. This is much under the specific gravity of the
* Pogg. Ann., civ, 5382, 1858.
356 Palmer—Arrizonite, Ferric Metatitanate.
more common varieties of ilmenite (4°7 to 4:9), and is only
slightly above that of arizonite (4°25).
Even more closely related to arizonite is a titanic iron sand
from Brazil, described by J. B. Mackintosh.* The numerical
data there given for the Brazilian sand are:
OS Rene ep im rae Meo ah 2 ONC
RG SO) Gt aa ae ee ae
FeO Mea ae en oe 4°90
Mi Ou tia oh his eae ei ee eee WES
SiO ie ecg Le earns
99°10
Specific gravity 4:2.
Mackintosh’s results indicate that the mineral was a mixture
of about 85 per cent ferric titanate, with 15 per cent ferrous
titanate. The concordance of the specific gravity of the Bra-
zilian sand with that of arizonite, and the preponderance in it
of ferric titanate, suggest the propriety of regarding this sandt
as an impure arizonite rather than as a variety of ilmenite.
Chemical Laboratory,
U. 8. Geological Survey.
* This Journal, xxix, p. 342, 1885.
+ Dana, System of Mineralogy, 6th edition, page 218. Ilmenite, Brazil,
Analysis No. 5.
,
Taylor— Retardation of Alpha Rays by Metals. 357
Art. XXX VI.—On the Retardation of Alpha Rays by Metals
and Gases ; by T. 8. Taytor.
[Contributions from the Sloane Physical Laboratory of Yale University. ]
Introduction.
In a preliminary paper* “On the Retardation of Alpha
Rays by Metal Foils and its Variation with the Speed of the
Alpha Particles,’ the writer described some experiments
which showed clearly that the air-equivalents of metal foils
decrease with the range of the alpha particles entering
the foils.¢ By “air equivalent” is meant the amount by
which the range of the a-particles in air is cut down by their
passage through the foil. It was shown that the change in
the air- equivalents i is small for thin foils of the lighter metals
when the speed of the alpha particles entering the sheets is
high; but, when the speed of the particles is low for thin
sheets or when the sheets are thicker, the change becomes
quite marked. A comparison of the’ change for sheets of
different metals of nearly equal air-equivalent showed the rate
of change to be in the order of the atomic weights of the
metals. The results obtained in these experiments were not suffi-
cient to furnish an explanation of the phenomenon; but the
continuation of the experiments during the last year under
somewhat different conditions has furnished results which do
lead to conclusions of some interest.
Scattering of the Alpha Rays.
In the determination of the variation in the air-equivalents
with the speed of the alpha particle as described in the paper
cited above, the source of rays (polonium), with the metal sheet
over it, was set at such a distance from the ionization chamber
that some part of the top, or nearly horizontal portion, of the
Bragg ionization curve fell within the ionization chamber. A
slight increase in the range of the particle in this portion of the
curve corresponds to a considerable increase in the ionization.
* This Journal, vol. xxvi, pp. 169-179, Sept., 1908.
+The phenomenon upon which this work was based was first observed by
Mme. Curie and has later been investigated by several others. Bragg &
Kleeman (Phil. Mag., Sept, 1905, and April, 1907) observed that the stopping
power of a metal was not independent of the speed. Kucera & Masek (Phys.
Zeitschr., xix, pp. 630-40, 1906), and Meitner (Phys. Zeitschr., viii, 489,
1907), ascribe the effect to a difference in the amount of scattering. McClung
(Phil. Mag., Jan., 1906), Rutherford (Phil. Mag., Aug., 1906), and Levin
(Phys. Zeitschr., xv, 519-521, 1906) obtained results which indicate that
each successive layer of aluminium foil diminishes the range of the a-parti-
cle by the same amount.
Am. Jour. ScI.—FourTH SERIES, Vou. XXVIII, No. 166.—Octossr, 1909.
~
358 ~ TLaylor—Retardation of Alpha Rays by Metals.
With the polonium set at a definite distance from the ioniza-
tion chamber, it was found that, when the metal sheet was
moved away from the polonium toward the ionization chamber,
the ionization increased. This increase in the ionization was
attributed to the alpha particle having a greater velocity (or
range) upon entering the chamber when the sheet was near the
chamber than it had when the sheet was at a distance from the
chamber. Hence the metal sheet did not cut down the range
of the particle so much when the sheet was at a distance from
the polonium as it did when near the polonium. As a prelim-
inary to more extensive experiments by this method, two tests
were made to ascertain whether a scattering of the rays could
explain the increase in the ionization observed when the metal
sheets were moved away from the polonium towards the
ionization chamber. |
first test.—Any marked scattering of the rays by the foils
would change the shape of the cone of rays and especially the
form of the top portion of the cone. ‘The slope of the top,
or nearly horizontal portion, of the Brage ionization curve, as
well as the value of the maximum ionization, depend upon the
form of the cone of rays arriving at the ionization ehamber.
Thus, if scattering of the rays exist to a very marked degree,
it might be expected that differences between the slope and
form of the two Bragg curves obtained with and without the
metal foil over the polonium could be readily detected. With
polonium as the source of rays, numerous determinations of
the Bragg curves, both with and without the various foils over
the polonium, were made. A study of these curves showed
them to run parallel to each other and to give the same value
of the maximum ionization. The effect of putting the foils
over the polonium was merely to diminish all the ordinates of
the curves by the same amount.
Second test.—An iris diaphragm whose circular opening
could be adjusted to any desired diameter between 0°5 and
55°™s was constructed of thin sheets of brass and placed
directly below the ionization chamber. The center of the
opening of the diaphragm was directly below the center of the
ionization chamber. With the source of rays (radium Q) at
such a distance from the ionization chamber that the chamber
cut the top portion of the Bragg curve, the ionization was meas-
ured for various distances of the metal sheets above the source
of rays ; first with the diaphragm open and then with the open-
ing in the diaphragm of such diameter as to just limit the geo-
metrical beam of rays, or to cut off the edge of the beam. For any
given position of the sheet above the source of rays, the ioniza-
tion was always greater when the diaphragm was completely
open than it was when the diaphragm just limited the beam.
Taylor—Retardation of Alpha Rays by Metals. 359
However, the difference between the ionization in the two
cases was a constant value for all positions of the metal sheets
above the source of rays. This difference would not be a
constant quantity if the scattering of the rays was the occasion
of the increase in the ionization produced by moving the metal
sheets away from the source of rays. On the contrary, the
difference between the ionizations with and without the
diaphragm limiting the geometrical beam of rays would be
greater when the sheet is far away from the source of rays
than when it is near the source of rays if scattering of the rays
by the foils was the cause of the increase in the ionization.
The fact that the ionization was greater with the diaphragm —
open than when it just limited the cone of rays signifies that
more alpha par ticles get into the ionization chamber in the
former than in the latter case, and therefore confirms the exist-
ence of scattering of the rays by metal foils as found by Geiger.*
These two methods of investigation, although in the case of
the latter showing the existence of the scattering of the rays,
seem to be sufficient to preclude scattering as an explanation
for the so-called decrease in the air-equivalents of the metal
sheets as they are moved away from the polonium. By
measuring the ionizations with and without the diaphragm
limiting the cone of rays when there was not a metal sheet
over the source of rays, it was found that the ionization was
greater in the latter than in the former case, which shows that
the rays are scattered by air as well as by metals. These
methods, however, are not particularly suitable for measuring
the amount of the scattering, and hence no comparison ‘as to
how much each metal scatters the rays was attempted. The
important fact is that the effect under consideration is not
influenced by the scatterig of the rays.
Continuation of Haperiments.
In the first experiments polonium had been used as the
source of rays, but in order to extend the study to alpha par-
ticles of higher range, radium C has been used in the present
experiments. This made it possible to use foils of greater
thickness than had been previously used. A thin aluminium
foil covered with a thin coating of lacquer was put directly
over a capsule containing a thin film of pure radium bromide
in order to prevent escape of the emanation. The hole in the
brass plug over the radium bromide was of such dimensions
that the cone of rays emerging from it fell well within the
limits of the ionization chamber. The radium bromide was
set at such a distance from the ionization chamber that a part
*Proceedings of the Royal Society, Series A, vol. lxxxi, No. 546, page
174.
360 Taylor—Retardation of Alpha Rays by Metals.
of the top, or slightly inclined portion, of the Bragg ioniza-
tion curve due to the a-particles from radium C fell within
the chamber, and the air-equivalents of the various metal
sheets determined at various points in the path of the rays in
exactly the same manner as that used in the first experiments.*
The rays of shorter range than those of radium C had no
effect upon the results since they did not reach the ionization
chamber. Beta and gamma rays are also given off by the
radium bromide, but the ionization produced by them can be
considered as a constant value over the part of the path used
and consequently the effect due to them is only a shifting of
the curves to the right parallel to themselves, which would
have no effect upon the results under consideration.
In Column 1, Table I, are given the different metal sheets
used in the experiments. Column 2 contains the thickness in
centimeters of the respective sheets. Column 3 has the air-
equivalents of the sheets as measured directly when the sheets
were nearest the source of rays. Column 4 contains the ratios
of the air-equivalents to the thickness of the respective metals.
The last three lines of the table will be referred to later.
The air-equivalents of the sheets given in Column 1, Table [,
as determined by an improved method for any position of
this sheet, are given in Table II.
The aluminum foil over the radium to prevent the escape of
the emanation cut down the range of the a-particles 0°46.
TasieE I.
1h iu III IV
Metal Thickness Air-equivalent
Sheets in cms. in cms. Ratio
AAU re eae Lie elOms 0°719 567 cae
PB Aisa IEE 0'980 56350 1G;
Or Aus ae. 3 2°50 X 105, 1°375 5°50 X 107
DD Ameen nay 22 350X105 1°900 By Deen
JAS Siete s 3786 X< 10x, OSE 2°61 X 10°
Bmpr ss ci T-99>AN0m; 1°995 2°48 le
BaNae fed Cie rs e 2°84 10~* 1:104 3°88 x 10:
By Pigseee ose abe SS OS 1°396 3°40 X 10°
OOF be eae 6°95 X 10° 2°325 3°34 <x 10°
AUN 2 Be eo) el Om 0°597 1°79 1
BAN see ies Bh <n 1°209 1°79 CE
CFE Es eae 10°40 X10“ 1°803 ITS Se G5
DATES © eG Oates 2°672 1°66 X 10°
Hydrogen Sheets
A hydrogen... 1°07 2 ODail 215 400m
B hydrogen... 1:93 0°428 2°21 CVn
C hydrogen... - 3°23 0°762 2°36 x 10a
* Loc. cit., pp. 173-175.
Taylor—Retardation of Alpha Rays by Metals. 361
Papin tk
Range
in cms. of
entering
a-par-
ticle A Al B Al C Al DrAT A Au BAuw GAu .D Au
fe O97. 4 1-209: .1°803 . 2672 0:719 -0°980 . 3% —1°900
5-3 ate L206 61-792. 2:659 —0:706:-0:966 13529. 1869
Pree sort 20)2,- 1:78t. 2-644 ~ 0°693.> 0:947 . 1328 183%
4°5 0°597 1:198 1°769 2°628 0°680 0:929 1°303 1°802
4°] ogee 103~ b(o7 o2-608--0°668° 0-910... 1276 £763
Pesaro bs, 1-742 2582 0:657 ~ O°889. 1-248. -1:720
so) 0596 17178 1°724 0644 0866 1°214 1°659
me 07595 -1°168.° 1°705 07630" 0:63) IIS) 598
fa 2 O-D92 1:152 0°616 0-805 1°127
Zor 0-584. Lidl 0°600 0°757
7 07570 0°582
13 -0°555
Range
in ems. of
entering
a-par-
pee Aven §=6€6BSnl6L UA Pb)! LB Pb 6 6=6C. Pb. Paper Celloidin
meee Ott L995" - P-hO4 (1°396. 2:325 1°020. 0°520
mart OO - 1-980 ):085- 1371. .2°596 ss S
499 0°993 1°960 1:064 1°343 2°260 8 re
45 0984 1°9388 1:°042 1°320 2°220 oe ce
meeeeO-o7 et. 1-9t4 17020" 1-289 2-180 a ae
mar O-9571. 1°884° 07999 1:263 .2°124 ss He
ae 07941 1:845 0°977 1-232 2°046 a EF
Beer O92 § 1°795---0°950 ~ .1°200 es BS
2°35 0°902 0°923 1°168 Ss
2A. 07882 0°888 nie
17 3=60°853 §
1°3 “ce
The height of the plug containing the radium was 0:9™ above
the radium. Therefore the maximum available range of the
alpha particles entering the sheet is 5°70. The values of the
air-equivalents for each of the metal sheets in Table II repre-
sent the average results obtained from a series of from six to
ten separate determinations, the details of which have been
omitted for the sake of brevity.
Experiments were also made with sheets of paper and cel-
loidin.* Two sheets of paper of about 1 and 2°™S air-equivalent
respectively, and three sheets of celloidin of air-equivalents of
the order of 0°5, 1:0 and 2°0°™* respectively were used. For
these sheets of paper and celloidin, the ionization did not
increase as the sheets were moved away from the radium, but
* Celloidin is a specially pure preparation of collodion.
362 Taylor—Retardation of Alpha Rays by Metals.
had the same value for all positions of the sheets, and hence
their air-equivalents remained constant.
The behavior of the sheets of paper and celloidin, the
atomic weights* of which are about the same as that of air,
suggested the idea of undertaking to obtain sheets of some
substance such as hydrogen whose atomic weight is less than
that of air. For this purpose a ring about one centimeter
wide was cut froma brass tube six centimeters in diameter
and two small brass tubes were put in the ring diametrically
opposite each other. Thin films of celloidin were stretched
across each side of the ring and held in place by universal
wax. This formed a cell which could be filled with hydrogen
and then used in the same manner as the metal foils. To be
certain that the cell was always full of hydrogen a slight cur-
rent of the gas was kept flowing through it all the time dur-
ing an experiment. A current of air was kept circulating
through the case surrounding the apparatus in order to pre-
vent the hydrogen, that might possibly leak from the cell, from
entering the ionization chamber. The air-equivalent of the
hydrogen cell or sheet when 0:9 from the radium was deter-
mined by plotting the ionization curve first with hydrogen and
then with air in the cell. The ordinates of the latter curve
were all increased by the thickness of the cell of hydrogen,
which gave the position of the curve if the cell had been
evacuated. The difference between the ordinates of the two
curves corresponding to a given abscissa was the air-equiva-
lent of the hydrogen sheet.
When the cell containing the hydrogen was moved away
from the radium, which was kept at a given position as in the
previous cases, it was found that the ionization decreased, which
signified that the total range in air of the alpha particle was
less when the hydrogen sheet was far away from the radium
than when it was near the radium. Thus the amount by
which the range of the alpha particle was cut down by its
passage through the cell was greater when the cell was at a
distance from the radium than it was when it was near the
radium. Consequently the air-equivalent of the hydrogen
cell zncreased as the range of the entering alpha particle
decreased. The particles had to pass through the celloidin
sheets, but this did not influence the effect because, as we have
seen, the amount by which the range was cut down by the
celloidin sheets was constant for all positions of the cell.
Determinations of the air-equivalents in centimeters of three
hydrogen cells given in Table I were made for various dis
tances of the cell from the radium and the results obtained
are recorded in Table III.
* By atomic weight of air, paper and celloidin is meant the average
weight of the constituent atoms.
Taylor —Retardation of Alpha Rays by Metals. 363
Taste III.
Range of the
a-particle upon
entering the
hydrogen A hydrogen B hydrogen C hydrogen
ao 0°231 0°428 0°762
4°8 0°235 0°434 0°776
4°4 0:24] 0°442 0°791
4°0 052477 0°451 0°807
3°6 0°254 0°460 0°831
3°2 0°262 0°470 0°861
2°8 0°271 0°483 0°896
2°4- 0°283 0°499 0°938
The reason the maximum range here is 5:°2™5 instead of
5-7-™S, as it was in Tabie II, is because the air-equivalent of the
lower film of celloidin must be subtracted, since the alpha
particles must pass through it before entering the hydrogen.
The air-equivalent of the lower film was 0:5°°,
Although the air-equivalents of the celloidin sheets remained
constant, it seemed probable, from the behavior of the hydrogen
sheets, that if the same experiments were performed in an
atmosphere of hydrogen, the .hydrogen-equivalent* of the
~ eelloidin sheet would not remain constant, but would decrease
as the range of the alpha particles decreased. To investigate
this point the apparatus was enclosed in an air-tight sheet
iron case, which by several partial evacuations and refillings
could be filled with practically pure hydrogen. With polonium
as the source of rays the hydrogen-equivalents in centimeters
of sheets of celloidin, aluminium, tin, and gold were deter-
mined for various distances of the sheets from the polonium.
Only the results for the celloidin and A gold are given in
Table IV, as they are sufficient to illustrate the point in question.
TaslLe IV.
Range in H of en- | |
tering particle __/13°0 |12°6 |12:2 |11°8 |11-4 {11:0 |10°6 |10°2 | 9°8 | 9-4
Celloidin ________- 23-20|23-08 22-96)22-80|22-64 22-48|22-32|22-16 21-88 /21-60
Meeold.. 2... ”|27-97/27°55 27-11 126-67 26-23125-75)25-17/24-49 23-91 23-01
The curves in figure 1 represent the results recorded in
Tables II, II, and IV. By noting the slopes of the curves
some comparison of the rates, at which the air- equivalents of
the various sheets change, can be obtained. Taking the
general slope of each curve and dividing it into the air-
equivalent of the corresponding sheet when 0:95 from the
radium, it is found that for a given metal the quotient thus
* The hydrogen-equivalent is the amount by which the range of the a-
particles in hydrogen is cut down by their passage through the sheet.
364 TLaylor—fetardation of Alpha Rays by Metals.
obtained is nearly constant for all the sheets of the metal.
This is shown in column 4, Table V. Thus for sheets of the
same metal the rate at which the air-equivalent of each sheet
changes with a change in the range of the entering a-particles, —
is proportional to its air-equivalent when nearest the radium.
The approximately constant numbers in column 6, Table V
show that the percentage rate of change in the air-equivalent
for any metal is nearly proportional to the square root of the
atomic weight. The agreement of the values in columns 4
and 6, Table V is as good as could be expected since the slopes
of the curves in figure 1 could only be determined roughly.
The proportionality is indeed only approximate, since the
curve for any one sheet does not have a constant slope.
TasLe V. |
Slopes Air- Mean
of equiva- ratio
Sheets curves lents Ratio Vatomic wt. WVatomic wt.
A Au.. 0 032 0°719 DBASE TIO
B Au.. 0°051 0°980 1°92 x 10°
C Au_- 0°064 1°375 2°15. 10°
D Au.. 0°100 1°900 1°90 x 10° 14°05 28°80
A Sn... 0°052 1011 3°16 107
B Sn-- 0°068 1°995 B17 C00: 10°91 34°34
A Pb..- 0°053 1°104 2°08 x 10°
Bebe 0:071 1°396 1:96 x 10°
C Pb.. 0°110 2°325 2°11 >< 10' 14°38 29°38
A Al.- 0°010 0°597 OO SOs
By Ale: 0°020 1°209 6°04 x 10°
CAIee 0,033 1°803 5°48 x 10° 5°19 30°41
DivAle: 0°045 2°672 5°93 x 10°
A H... —0°020 0231 1:16 10°
B H._. —0:034 0°428 ela S<LO-
C H_.. —0:064 0°762 SSO
For the thin sheet of aluminium the air-equivalent is almost
constant for the higher ranges or speeds, but as the speed of
the entering alpha particle decreases the air-equivalent decreases
slowly and in the lower ranges the decrease becomes quite
apparent. For the thicker sheets of aluminium the change is
more marked even for the higher ranges. The statements of
McClung, Levin and Rutherford that equal successive layers
of aluminium foil diminish the range of the alpha particles by
equal amounts seem to hold true for thin sheets of foil when
the range is high; but when the metal sheet is thicker, or for
thin sheets when the range is low, it does not hold. The
slight difference, however, in the air-equivalent of the thin
foil when near and far away from the polonium, would scarcely
365
Taylor— Retardation of Alpha Rays by Metals.
Pree
ig
oan oak nen
2 See Saas
FN : ee eee
Fie. 1. For the portion of the figure containing the curves designated as:
‘A Gold in Hydrogen,” “ Gelloidin in Hydrogen,’ 7and ‘‘ A Geld in Air,’
ne abscissas are the ranges in hydrogen of the alpha particles when ae
enter the sheets and the ordinates are the hydrogen-equivalents of the
sheets. For the other part of the figure the abscissas are the ranges in air
of the alpha particles when they enter the sheets and the ordinates are the
air-equivalents.
366 = Taylor—fetardation of Alpha Rays by Metals.
be detected by measuring directly the air-equivalent in the
two positions. This is probably the explanation of the above
statements by McClung, Levin and Rutherford.
Since the air-equivalent of a metal sheet decreases with the
speed of the alpha particle entering it, the ratio of the air-equiva-
lent to the thickness of a given sheet of metal should be less
than the same ratio for a thinner sheet of the same metal.
This is shown to be true by the last column of Table I. For
the hydrogen sheets, on the contrary, the same ratio should
increase as the thickness of the cell or sheet of hydrogen
increases. This is also confirmed by the last column of
Table I. | : |
While the air-equivalent of the sheet of celloidin remains
constant the hydrogen-equivalent of the same does not remain
constant but decreases as the range of the alpha particle in
hydrogen decreases. The curve “COelloidin in Hydrogen,”
figure 1, which was plotted from the results recorded in ‘Table
IV, illustrates this point. It is to be noted also from the curve
“A Gold in Hydrogen,” figure 1, that the rate at which the
hydrogen-equwalent of the A gold decreases is much greater
than the rate at which its avr-equivalent decreases. The curve
designated “A Gold in Air,” figure 1, is the portion of the
“A Gold” curve in the same figure that lies to the left of the
abscissa, 3°0. The codrdinates of that portion of the curve
are magnified about 4 2/3 times so as to be plotted on the
same scale as the curves obtained in the hydrogen atmosphere.
4 2/3 is the ratio of the thickness of a hydrogen sheet to its
air-equivalent when near the radium. The slope of the curve
‘“A Gold in Air” is practically the same as that of “ Cel-
loidin in Hydrogen,’ as can be seen from the figure. The
angle which the curve “A Gold in Hydrogen” makes with —
the curve “A Gold in Air” is about the same as the angle
which the curve “Celloidin in Hydrogen” makes with the
axis of abscissas. The slope of the curve “A Goldin Hydrogen”
is nearly 3 3/4 times the slope of the curve “Celloidin in
Hydrogen.” But 3 3/4 is the ratio of the square root of the
atomic weight of gold to that of air Pee: = 5154 |
Hence the rates, at which the hydrogen-equivalents of the
gold and celloidin sheets decrease with the speed of the alpha
particle entering the sheets, are proportional to the square
roots of their respective atomic weights. Moreover the slope
of the curve ‘“Celloidin in Hydrogen” is numerically equal.
(but of opposite sign) to the slope of the curve “ B Hydrogen”
in air. The hydrogen-equivalent of the celloidin sheet was
somewhat larger than the thickness of the “ B Hydrogen”
cell, but it seems entirely proper to conclude that the rate at
Taylor— Retardation of Alpha Rays by Metals. 367
which the hydrogen-equivalent of the celloidin sheet decreases
with the speed of the alpha particle, is the same as the rate at
which the air-equivalent of the B hydrogen increases as the
speed of the entering alpha particle decreases.
The possibility that the observed variations in the ionization,
which have been taken to be the measures of the changes in
the air-equivalents, may be due to secondary rays is precluded
by the fact that numerous direct determinations of the Bragg
ionization curves with and without the metal sheets near the
polonium and again near the ionization chamber, showed no
irregularities in the curves, as would be expected were second-
ary rays present in any appreciable amount. The behavior of
the air-equivalents of the hydrogen sheets in no way conforms
to what might be expected to be produced by secondary rays.
The increasing of the air-equivalents of the hydrogen sheets
and the decreasing of the hydrogen-equivalents of the celloidin
sheets when moved away from the source of rays gave occasion
for suspecting that some differences might be found to exist
between the Bragg ionization curves obtained in atmospheres
of air and hydrogen respectively. ‘To determine these curves
use was made of an apparatus, constructed for Mr. F. E.
Wheelock of this Laboratory, which was similar to the one
used thus far in the work except that the vessel enclosing the
main part of the apparatus could be completely exhausted.
To make any comparison of the two ionization curves it was
necessary to determine them under similar conditions, 1. e. the
same source of rays was used in the two cases and the pressure
of the air was so reduced as to make the range of the a-particles
in air equal to their range in hydrogen at normal pressure.
Polonium was used as the source of rays and several Bragg
curves were obtained in hydrogen at normal pressure and in
air at a reduced pressure of about 17°™* of mercury. ‘Two of
the curves are shown in figure 2. The dotted portion of each
curve is assumed to be the form it would take were it possible
to move the polonium entirely up to the ionization chamber.
At all events, these assumed portions of the curves can differ
but little from what the actual curves would be.
It is to be observed that the two curves in figure 2 present
slight differences in form. The probable interpretation
of these differences will now be considered. Any given
abscissa of either curve is a measure of the ionization produced
by the particles in the gas in the chamber when the polonium
was at a distance from the chamber represented by the ordinate
corresponding to the given abscissa. Consequently the total
area enclosed by the two axes of reference and either curve is
proportional to the total ionization produced in the gas in
which the curve was determined. By measuring these areas
368 Taylor—fetardation of Alpha Rays by Metals.
with a planimeter, it was found they were equal. This con-
firms the observations by Bragg” that the total ionization pro-
duced by the alpha particle in air is the same as that in hydro-
gen. From the curves of figure 2 it is seen that when the
speed of the a-particle is high more ions are produced per
centimeter of path in air than in hydrogen, but when the
speed is low more ious are produced per centimeter in hydro-
gen than in air.
0. 3 e 3 4 1. 6) 7) 1ereoonete
Fic. 2. The ordinates of the curves are the distances in centimeters of
the polonium from the ionization chamber. The abscissas are the defiec-
tions in centimeters of the electrometer needle per second. Curve I was
obtained in air at a reduced pressure of about 17 centimeters of mercury.
Curve II was obtained in hydrogen at normal pressure.
* Phil. Mag., March, 1907, p. 333.
Taylor— Retardation of Alpha Rays by Metals. 369
Let us suppose that for a given speed of the alpha particle
the amount of energy required to produce an ion is the same
in all substances. Then for air we would have the relation
al, = — f(V) dE,
The corresponding relation in hydrogen is
di, = — f(V) dE.
Dividing the former by the latter we have
Gl op iV Yd,
ai, Saf (Vv). dB,
which for a given speed V in each gas reduces to |
di, d EK,
eee. aE,
From this it is seen that for a given speed of the alpha particle
the ratio, of the rates of the consumption of the energy in
producing ions in air and hydrogen, is equal to the ratio of the
rates at which the ionization is produced in the respective
gases. On the basis of our hypothesis let us consider the ratios
of the energies consumed in the 4th and 138th centimeters
(fig. 2) of the path of the particle in air and hydrogen. This
ratio for the fourth centimeter of the path is proportional to
area cd 43 ¢
area ab 43 a
produced in the gases. The corresponding ratio for the 13th
atea €,.f, 13,12, 6;
area g, h, 13,12, 9
is seen from the figure to be greater than the latter. Moreover,
it is also seen that the ratio of the energy of the a-particle
absorbed by any given centimeter of air to the energy
absorbed by the corresponding centimeter of hydrogen, is always
greater than the corresponding ratio for the centimeter just
beyond the given one. This is in agreement with the results
obtained for the air-equivalents of the hydrogen cells ; because
the increase in their air-equivalents as the range decreases is
due to the fact that the ratio of the energy absorbed by the
hydrogen cell to the energy that would be consumed by the
air which it displaces, continually increases as the cell is moved
away from the source of rays. The thicker the cell the more
rapid would be the rate of increase, as could be seen by com-
paring the areas which represent the ionization in, say two
centimeters of air and hydrogen respectively in figure 3 in
two different positions. The increase in the ratio of the ener-
since the areas are proportional to the ionizations
The former ratio
centimeter is equal to
370 TLaylor—Letardation of Alpha Rays by Metals.
gies consumed in air and hydrogen respectively is in agreement
also with the decrease in the hydrogen-equivalent of the
celloidin film.
Still making use of our hypothesis, the ratio of the energy, —
consumed in the 9th and 10th centimeters of air at reduced
pressure, to that consumed in the same centimeters of hydrogen
: oe : 312
at normal pressure, is expressed by the fraction S0E: The
same ratio for the 13th and 14th centimeters is = These
at
ratios were obtained by measuring with a planimeter the areas
in figure 2. The former ratio divided by the latter gives 1°10.
Since the hydrogen equivalent of the celloidin film is but
shghtly more than two centimeters, the ratio of its values at 9
and 13°™* respectively from the polonium should be the same
as the above ratio. The hydrogen equivalents of the film in
the two positions (see figure 1) are 2°320 and 2°120°™ respect-
ively, and the ratio of the former to the latter is 1:09, which
differs little from the calculated ratio 1:10 given above.
Hence it is seen that the differences between the curves of
figure 2 are sufficient to account for the change in the
hydrogen-equivalent of the celloidin film and consequently for
the increase in the air-equivalents of the hydrogen sheets when
moved away from the source of rays. This agreement between |
the relative ionizations and the relative losses of energy of the
particle in the two gases gives a considerable degree of
probability to our hypothesis connecting the relation of the
ionization produced to the energy consumed.
The experimental results show that the air-equivalents of the
metal sheets decrease with the speed of the alpha particle, and
hence the ratio of the energy of the alpha particle, consumed
by its passage through a sheet of metal, to the energy that
would be consumed by one centimeter of air at the same
point in the path of the particle, decreases as the range of the
alpha: particle decreases. The behavior of the metal sheets
relative to the air is entirely analogous to the behavior of the
air, or celloidin relative to hydrogen. Consequently if it were
possible to measure the ionization produced by the alpha
particle at different points in the path of the rays in the
metals, and if the ionization curves were plotted on the same
scale as those shown for air and hydrogen, figure 2, it is prob-
able that the curves for the metals would all present some
such differences from the air curve as those existing between
the air and hydrogen curves. Moreover these differences might
be expected to be such as to agree with the different rates at
which the air-equivalents of the different metal sheets change.
Taylor— Retardation of Alpha Rays by Metals. 371
In the upper portion, the curve for gold would probably lie
within the air curve about the same amount as the air curve
does within the hydrogen curve, figure 2; and in the lower
portion the curve for gold would probably lie without the air
curve by the same amount as the air curve does without the
hydrogen curve. At least some such differences would be in
accordance with the square root law, since the square root of
the atomic weight of air is a mean proportional between the
square root of the atomic weights of gold and hydrogen. The
curves for the other metals would occupy intermediate posi-
tions between the curves for gold and air.
We have seen that for different metal sheets of about the
same air-equivalents the rates at which the air-equivalents
decrease with speed of the alpha particle, are proportional to
the square roots of the atomic weights of the respective metals.
- Consequently the rates of decrease of the ratios of the quan-
tities of energy used up in the sheets to the energy that would
be consumed by a centimeter of air at the same positions in
the path of the particle decreases also as the square roots of
the atomic weights of the respective metals. On the basis of
our hypothesis that for a given speed of the alpha particle the
same amount of energy is required to produce an ion in all
substances, and from the results in our experiments, 1t appears
indeed very probable that for the high velocities the alpha
particle loses its energy, in going through a substance, more
rapidly the higher the atomic weight of the substance; but as
the speed of the alpha particle becomes less this changes, until
for the low velocities the loss of the energy of the particle is
more rapid the lower the atomic weight of the substance.
In conclusion I wish to express my gratitude to Professor
Bumstead, at whose suggestion these experiments were under-
taken, for his valuable suggestions and interest in the work ;
also to Professor Boltwood, who kindly prepared the polonium
and secured the radium bromide for me, and gave me many
valuable suggestions.
Summary of Results.
1. The air-equivalents of metal foils decrease with the speed
of the alpha particles entering them. The decrease is very
small for thin foils of the lighter metals when the speed of the
a-particles is high; but when the speed is low for thin sheets,
or when the sheets are thicker, the change becomes more marked.
For different sheets of the same metal the rates of change are
proportional to the air-equivalents of the sheets. For sheets of
different metals of equal air-equivalents the rates of change
are approximately proportional to the square roots of the
respective atomic weights. :
372 Taylor—Retardation of Alpha Rays by Metals.
2. The air-equivalents of hydrogen cells or sheets increase
as the speed of the entering particle decreases, while the air-
equivalents of sheets of paper and celloidin remains constant.
3. The hydrogen-equivalents of sheets of paper, films of
celloidin, and air do not remain constant but decrease as the
speed of the alpha particle decreases. The rate at which the
hydrogen-equivalent of a celloidin film decreases with the
speed of the entering a-particle is numerically equal to the
rate at which the air-equivalent of a hydrogen sheet of corre-
sponding thickness increases.
4. The result obtained by Bragg, that the total ionization
produced by the alpha particle in air is the same as that in
hydrogen, is confirmed by a more direct method.
5. It is very probable that for the high ranges the a-particle
loses its energy, in passing through substances, more. rapidly
the higher the atomic weight of the substance; but that this
difference decreases slowly until in the low ranges the loss of
energy is the more rapid the lower the atomic weight of the
substance.
6. A comparison of the Bragg curves for air and hydregen
indicates that the large ionization at low ranges (knee of the
curve) is due at least in part to the fact that the particle loses
its energy more rapidly in this part of the range; and not
wholly to the higher ionizing efficiency of particles of low
speed.
I. Bowman—Physiography of the Central Andes. 373
Art. XXXVII.—The Physiography of the Central Andes:
LIT. The Eastern Andes; by Isatan Bowman.
Durine the field examination of the eastern Andes of
Bolivia, not only were the local geology and physiography
noted, but many widely separated commanding points were
also gained from which was viewed the general aspect of the
eastern plateau. The results were everywhere strikingly
similar. The conclusions based upon an examination of these
wide expanses of the plateau surface and their discordance
with respect to structure harmonize with those resting upon a
study of drainage features and lead inevitably to the conclu-
sion that peneplanation is the dominating fact in the physi-
ography of the region. Lest it seem that this view is held
without sufficient consideration of the geologic structure and
of the relation of the plane of baseleveling to it, the following
geologic descriptions are introduced. They but serve to
emphasize the conclusions already stated by the striking
structural vayjations they indicate, variations practically unex-
pressed in the plateau surface, save where residual masses have
survived the baseleveling process.
Geologic Features.
The rocks of the eastern Andes may be roughly classified
into two great groups, the eastern sandstone series and the
western schistose series. The sandstone series consists of
shales, conglomerates and sandstones; the schistose series
consists of slates, quartzites and quartzite schists. Both are
structurally disturbed, but the disturbances in the schists are
of a more profound order and have resulted in metamorphic
effects whereby the schistose structure was imposed upon the
entire western series. Every gradation may be observed in the
scale of these disturbances from those of microscopic to those
of mountainous proportions. In all sections there are notable
intrusions of igneous material. In the slates of Santa Vera
Cruz it is quartz porphyry and granite, the lead, tin and zine
of commercial interest being found in fissures of the quartz
porphyry. In the western series of rocks almost every variety
of geologic structure may be found in a day’s ride from east
to west across the grain of the rock; in the eastern sandstone
series the structures vary from folds to block-faulted mono-
clines, so that within limited areas the latter structures show
dip and strike of more or less constant value.
Specific structural values for definite localities are almost
without physiographic interest or importance, so generally do
they conform to the generalizations that have just been noted.
Am. Jour. Sci.—Fourts Series, Vou. XXVIII, No. 166.—OctozeEr, 1909.
25 :
374 I. Bowman—Physiography of the Oentral Andes.
The dip and strike are, as arule, so irregular in value that both
specific and general values are almost without interest. In
general it may be said that the prevailing dip of the sand-
stones along the lower Juntas valley north and northeast
of Cochabamba is northwest or toward the axis of the
eastern highland, though there are frequent and important
exceptions to this generalization. Of frequent occurrence are
zones of crushing where incredibly minute and numerous dis-
turbances have resulted from the adjustment of great block-
like masses of sandstone on either side. There is notably
greater textural firmness to the sandstones and shales toward
the west; those toward the east are often so pliable as to fall
to pieces readily, though there are again many local excep-
tions to this condition. The whole sandstone series is unfossil-
iferous so far as we examined it and is marked throughout by
SCALE : 1! =400,000
oS 2 fe
VOCS A) (A .
SA
|
Lv,
Fic. 18. Rio Chaparé, eastern Bolivia, for fifty miles below Santa Rosa.
the development of coarse conglomeratic deposits interstratified
with finer textured layers. In many localities cross-bedding
may be observed, and this feature, while not everywhere dis-
played, is about as common in one section as another. An
unusual feature of the easternmost sandstone on the margin of
the plains was the presence in the parting planes of small clay
lenses a foot or so in length and a few inches thick. The clay
is moderately dry and soft and falls out of a broken fragment
of sandstone as a separate unit. These clay lenses, from their
position and the frequency of their occurrence, appear to
indicate a general process of flood-plain erosion whereby a clay
layer resting upon sand was eroded to the point where only
16°40'S
Q
S Pad
EES
SEcloa Rn’ .ay
I. Bowman—Physiography of the Central Andes. 375
fragments of the clay remained. These were then covered by
a second thick layer of sand and thus preserved.
The frequent occurrence of irregular and locally variable
conglomeratic layers throughout the sandstone series, the inter-
stratified clay lenses, the great thickness of the conglomerates
and coarse sandstones, establish the conclusion that the sand-
stone series represents a piedmont river deposit. As an index
of the close proximity of highland and aggrading flood-plain
upon which such coarse deposits were for med, might be cited
our observations upon the degree of coarseness of the bar
material in the Chaparé downstream from San Antonio at
the base of the Andes, fig. 18. At and above San Antonio
the river is full of bowlders, often of huge size. At Santa
Rosa, less than twenty miles away, the bars are composed of
sand and pebbles of 8,10, and 12 inches in diameter. Six
miles below Santa Rosa one can discern pebbles only in
patches upon the upstream sides of the bars, and fifteen miles
farther downstream, or forty miles by river and perhaps twenty
or twenty-five miles in a direct line from the edge of the
existing upland, it is impossible to find any pebbles whatever,—
the bars are wholly of sand. Such a distribution of coarse
material along the valley of the Chaparé supplies data for the
conclusion that the eastern front of the Andes was not far
from the conglomerate formation of a particular locality and
that the progressive eastward uplift of the Andes accounts for
the wide distribution of the conglomerates throughout the
sandstone series that now constitutes the eastern border of the
Andine Cordillera. This conclusion seems the more warrant-
able because the conditions of lofty mountains and adjacent
flat plains, with a strong and sudden break between, are now
most favorable for the widest development of conglomerates ;
and as we have just seen, these are now formed in an
extremely narrow belt (less than thirty miles) along the moun-
tain front.
This brief outline of the geologic structure of the region
may now well be followed by a word concerning the geologic
history of the central Andes as a whole. With these three
groups of facts before us—the structure, the geologic history,
and the general physiographic aspect of "the region—we shall
be prepared to discuss the physiographic conclusions and the
detailed stratigraphic and physiographic evidence upon which
they rest.
The western or Maritime Andes consist chiefly of Mesozoic
strata interstratified with and intruded by igneous rocks, and
are of later age than the eastern Andes. The whole rock series
is surmounted, in addition, by volcanic piles which give what-
ever variety and mountain alignment these mountains possess.
376 I. Bowman—Physiography of the Central Andes.
Between the western and the eastern Andes are ridges and
masses of rock of Devonian, Carboniferous, and Permian or
Triassic age, rising out of a creat infilling mass of alluvial
material derived from the adjacent highlands. In northern
Bolivia the first foldings of the eastern Andes took place in
very early times, but the effects of erosion and of tectonic
changes were such as to bring the entire area below sea level
at the beginning of the Carboniferous period. Before the
close of this period renewed elevation again exposed the sedi-
ments to erosion, and from this time on the geologic history
of the region consists of erosion and renewed folding accom-
panied by the intrusion of those granitic masses which now
constitute the cores of the highest chains. So. far as the
geologic record has been interpreted, the movements in the
eastern Andes seem to have been resumed in the Cretaceous
although the main central chain was outlined and its position
established at the end of the Paleozoic.*
The widely extended development of the Cretaceous hints
at the significant erosion that must have taken place on the
land area formed by the mountainmaking movement at
the end of the Paleozoic. “Marine Kreidefossilien wurden in
fast allen Teilen der Anden gefunden...” ¢
The western. Andes, on the other hand, were a region of
sedimentation down to the end of the Mesozoic, when moun-
tain-making movements began. This movement, however,
must be distinguished from that now in progress and described
in the preceding chapter. The movements of to-day are
broad and regional in their effects, and distinctly non-moun-
tainous in character.
In southern and eastern Bolivia the sediments are Cambrian
and Lower Silurian, with some traces of Devonian and
Carboniferous. The farther back geologic researches extend
the clearer it becomes established how general is the oceur-
rence of Paleozoic strata. Silurian and Devonian rocks oceur
widely distributed in every region of the continent, even in the
region which now has the most conspicuons mountain heights,
Silurian fossils occurring in the slates that form the highest
portions of the Nevadas of Quimsa Cruz, at 17,000 ft. Thick
strata of red Cretaceous sandstones also occur which, under
ordinary circumstances, are only preserved in troughs and folds.
This entire system of sediments “lies concordantly” except
*Condensed and adapted from the accounts of the geologic history of the
region in Expedition to Caupolican Bolivia, 1901-1902, by J. W. Evans
(The Geog. Jour., vol. xxii, pp. 631-634 et al., 1903); Stid- und Mittel-
Amerika, by W. Sievers (1903); The Continent of South America, by A. J.
Herbertson (1900) (Mills’ International Geography, pp. 816-817); Arch-
helenis und Archinotis, by H. von Ihering (1907).
+ Archhelenis und Archinotis, 1907, p. 99.
I. Bowman—Physiography of the Central Andes. 377
where the original concordance has been disturbed by differen-
tial movements associated with the folding which involved
both sedimentary series. In general the folding took place on
very broad lines and individual folds are often of great
dimensions.* The whole of the great region near and south
of Tarija consists of a series of shallow folds or parallel chains
of Silurian, Devonian, and Cretaceous deposits. The red
Cretaceous sandstones rim the outer edge of the entire eastern
Andine section of Bolivia, extending as far as explorations have
been carried toward the north. On the south they are said by
Hoek to be of marine origin; but farther north, in the valley
of the Juntas and the San Antonio they are certainly terres-
trial, carrying large proportions of conglomerate and cross-
bedded sandstone. (See p. 374.) Evans has describedt+ the
northeastern section of this marginal band of sandstones as
consisting of soft red sandstones and conglomerates overlying
harder sandstones in some places, or as a conglomerate resting
upon soft shaly sandstones in others. These observations and
our own in the valleys farther south, the Juntas and San
Antonio, certainly deny a marine origin to the sandstone series
of northeastern Bolivia. The age of the sandstones in these
northern locations is not fixed, however. They appear to have
the same structural relations to the older Paleozoic rocks as
the known Cretaceous sandstones farther south and like them
also to have been folded on a huge scale and in places bloci-
faulted. It may be necessary to assign a later age to them, a
point which seems difficult to clear up in the absence of fossils.
The equivalency of the non-marine red sandstones of eastern
Bolivia and the marine red bedsof known Cretaceous age
farther south was first suggested by Steinmann in 1891.+
The latest deposits in the central Andes whose age has been
positively identified by fossils are of Eocene age and occur
along the coast of northern and central Chile. Probable
Miocene beds of very limited development occur in northern
Chile,§ but neither they nor the Eocene shared in the mountain-
making movements of the late Mesozoic. The marine
Triassic and Jurassic have avery limited development and
occur only between 5° and 25° south latitude in the coastal
section of the continent.|
*Exploration in Bolivia, by H. Hoek (The Geog. Jour., vol. xxv, p.
510, 1905).
+ Expedition to Caupolican Bolivia, 1901-1902, by J.-W. Evans (The
Geograph. Jour., vol. xxii, pp. 607 and 614, 1908,.
{A Sketch of the Geology of South America (Amer. Naturalist, vol.
xxv, p. 858, 1891).
$ Moricke and Steinmann (N. Jahrbuch f. Min., etc., Beilagebd. x, p.
533, 1896).
| A Sketch of the Geology of South America. A paper by A. Steinmann
read before the Geol. Soc. Am., Aug. 25, 1891 (Amer. Naturalist, vol. xxv.
p. 857, Oct., 1891).
378 LI. Bowman—Phystography of the Central Andes.
The wide distribution of Cretaceous strata in Bolivia, north-
ern Peru, and Ecuador indicates how late was the formation of
the western Andes. Von Ihering* assigns the uplift of the
western ranges to the point of continuous extent from Colom-
bia to Bolivia to the same period in which the Antarctic region
sank and the bridge between Australia and South America
was destroyed, that is, to the EKocene. However, the absence
of the Upper Cretaceous and the exceedingly limited occurrence
of the Eocene, and probable Miocene, upon the western fringe
of the Maritime Andes would seem to be sufficient ground for
concluding that the formation of the western ranges was well
begun in the Cretaceous, though undoubtedly completed only
in the early Tertiary.
The occurrence of a widely developed baseleveled surface
now uplifted to a great height furnishes an interesting means
for the determination of recent geologic history. The
common physiographic history of the eastern and western
Andes, as indicated by the equally well-developed peneplain
formed upon both, is sufficient basis for the conclusion that the
mountain-making movements were completed with the formation
of the western Andes. From that time on, the history of both
orographie systems is written in terms of erosion cycles whose
development to different stages—the first to completion, the
second to maturity of form, and the third but fairly begun—
supplies us at once with the full means for topographic corre-
lation. The drainage features of southeastern Bolivia unite
with the topographic features to indicate that, whatever the
nature of the deformations that accompanied the regional
uplift of the peneplain, the peneplain was only developed after
the orogenic movements had occurred which involved the red
Cretaceous sandstones, for these are indicated by Hoek to “ lie
concordantly ” with respect to the older series of rocks, and
are involved with them in the same series of folds. The drain-
age relations support this view fully. The superposed drain-
age which cuts across hard and soft, across Silurian and Creta-
ceous alike, and is directed regardless of the structural axes,
clearly supports the fact already established by the topographic
features, that the peneplain was developed subsequent to that
orogenic movement which closed the Mesozoic era and finally
excluded the sea from that part of the continent now known
as the central Andes. We are therefore assured that pene-
planation followed the Mesozoic era. It must have occurred
some time during the Tertiary, although profound erosion and
an approach to peneplanation must have occurred in the
eastern Andes during the deposition of the Cretaceous and
Jurassic sediments that form the western Andes. This
* Archhelenis und Archinotis, 1907, pp. 118-119.
I. Bowman —Physiography of the Central Andes. 379
preparation of the eastern Andes, the more profoundly dis-
turbed of the two systems, for participation in the base-level-
ing that followed the formation of the western Andes,
undoubtedly accounts for the general development of the
peneplain upon both orographic systems. Our whole con-
ception of geologic time, and especially of the time required
for the completion of an erosion cycle, is so vague that neither
the termination of the first cycle nor the geologic age of the
mature slopes of the second can be fixed with any measure,
one might almost say with the least measure of certainty. IH,
however, the existence of the peneplain and of the mature
slopes of a later cycle are once established and the age of the
former determined to be later than the Cretaceous, we are pre-
pared to accept the conclusion that however small a portion
of geologic time remains, that portion can not fail to have
been long enough to produce the results observed. In short,
that it is our conception of geologic time and_ particularly
that portion of it since the Mesozoic that requires adjustment.
Current Hxplanation.
Inasmuch as the interpretations here presented differ radi-
cally from previous ones, a brief review of current descriptions
and explanations seems advisable. The descriptions of the
central Andes in standard general references have this in
common, that the mountain forms of both the eastern and
western “ranges” (plateaus) are described solely with refer-
eilee oO tie order or imitial upliit and the degree of
dissection tacitly assumed to have been accomplished in a
single cycle of erosion. “The eastern ranges were folded
earlier than the western ranges, where the folds are most
marked.”* ‘The western Cordillera is younger than the
eastern Cordillera and was covered by the sea during Paleo-
zoic and Mesozoic times, then uplifted to a great height and
still further modified by eruptive material even now, in many
places, in process of accumulation.” + These serve to indicate
the point concerning uplift, while the absence of any appre-
ciation of erosion cycles is recognized by the following
description, which may well serve as a type: “ In this ‘Bolivian
Switzerland’ .... amid a chaos of precipitous heights, detached
crests, and masses, thrown together without any apparent
order, it seems difficult to detect any general plan.” +t
Another point may here be noted concerning the interpre-
tations so far published. While all ascribe an earlier uplift to
*Herbertson, A. J., The Continent of South America (The International
Geography, p. 817, 1900).
+ A free translation of Sievers, Die West Cordillera (Siid- und Mittel-Amer-
ika, p. 390, 1903).
{ Keane, A. H., South America (Stanford’s Compendium of Geography,
p. 240, 1901).
380 L. Bowman—Physiography of the Central Andes.
the eastern Andes of Bolivia, no attempt is made to deal with
the topographic consequences of the greater erosion which,
under comparable conditions, must follow upon greater age,
except to say that the greater rainfall of the eastern Andes has
resulted in much deeper dissection. Now it has been shown
in the preceding chapter that, as compared with the eastern
Andes the western Andes are in a far younger state of topo-
graphic development; and that the uplifted and now moder-
ately well-dissected peneplain which forms the western Andes
of Bolivia was developed to a typical degree. This now
deformed peneplain is the dominating fact—the topographic
line, WA,
é cale, i:gec 000
PROVINCE OF
LAS YUNGAS
* CELIMANI
Fra. 14. Upper La Paz Valley, west of the Cordillera Real (from Conway,
Geog. Journal, 1900). Disregard scale ratio ; divisions express kilometers.
motif—of the landscape ; and stands out much more clearly, by
virtue of less dissection, than its continuation in the eastern
Andes. It is this form which led Phillipi* to deny the exist-
ence of a‘* Cordillerenkette ” in the western Andes because of
the general absence of mountain character. Since Philippi’s
day the suggestion seems to have passed unheeded except for
an occasional quotation, each new writer vying with his pre-
decessors in the use of adjectives fitly to describe the lofty
voleanoes and volcanic kncts while disregarding the pedestal
or platform on which they stand.
* Reise durch die Wiste Atacama, 1860 (quoted by Sievers, Siid- und
Mittel-Amerika, p. 381).
I, Bowman—Physiography of the Central Andes. 381
Such an interpretation of the central Andes as the quotations
afford not only leaves wholly out of consideration the latest
events in the geologic history of the region, but also disregards
some of the most obvious and important elements of form.
The persistence of these elements over a wide area lends to
their interpretation an importance equivalent to interpretations
of stratigraphic and paleontologic facts as leading to’a more
complete record of geologic events.
Fig. 15.
no
Fie. 15. A portion of Caupolican Bolivia (from Whitney, Evans, etc.,
Geog. Journal, 1903). Disregard scale ratio ; divisions express kilometers.
Features of the First Cycle of Erosion.
The more detailed examination of the physiography of the
eastern Andes of Bolivia may well begin with the great crown-
ing range of the whole region, the Cordillera Real (fig. 14).
Its structural features exhibit the solid geometry of the
eastern Andes in almost diagrammatic form. It consists of a
meridional axis of crystalline rocks—granites, gneisses, etc.—
382 L. Bowman— Physiography of the Central Andes.
and is flanked by metamorphosed sedimentary rocks—schists,
slates, quartzites, and the like—of Paleozoic age (Cambrian to
Lower Devonian), which dip away from the central axis.*
The whole series forms an involved anticlinal with a core of
granitic rock in the center. It is this granitic core which by
virtue of its superior hardness gives rise to the celebrated line
of lofty peaks running from Ancohuma to Illimani. Fifty
miles northeast of the main axis thus outlined are the Cusali
mountains (fig. 15), whose trend parallels that of the Cordillera
Real. They are composed of slates, sandstones and limestones
of Paleozoic age. For nearly another fifty miles are similar
parallel ranges of sandstone which terminate at the Bali-Susi
range, the last of the Andes mountains toward the northeast.+
Beyond is the great basin of the Amazon, which at even this
far inland point is but seven hundred feet above the level
of the sea. The Mesozoic sediments which form these out-
lying ranges are either unaltered or but slightly altered; and
neither in structure nor physical condition do they constitute
an integral portion of the Cordillera Real.
Southward across the La Paz valley the axis of the Cor-
dillera Real is continued in the Nevadas de Araca, Nevadas
de Quimsa Cruz, and Nevadas de Vera Cruz (sometimes
erroneously called the Santa Vela Cruz). These form a line
of heights as definite in trend and structure as the Cordillera
Real and continue the definite features of the latter southward
for nearly fifty miles. They are described by Steinmann and
Hoek as the direct extension of Illimani, not only as to geologic
but also as to geographic character.{ No volcanic material
is found in either of the mountain groups indicated. The
lofty snow-covered peaks are not a line of extinct volcanoes,
but a central core of highly resistant rock whose superior
hardness and greater initial elevation have preserved it from
the ultimate effects of the great denudation elsewhere recog-
nized.
The baseleveled surface developed about the western border
of the Cordillera Real can be clearly identified from El] Cum-
bre, north of La Paz. Looking south, southeast and southwest
from this position (about 13,000 ft. elevation), one sees in the
foreground the long slopes of the ampitheatral valley head
(in which lies the city of La Paz) descending to the valley
floor. In the middle distance, fig. 16, is the upper edge of
the valley, descending to the right as the piedmont alluvial
* Sievers, W., Stid- und Mittel-Amerika, pp. 381, 382, 1908.
+Expedition to Caupolican Bolivia, 1901-1902, by J. W. Evans (Geog.
Jour., vol. xxii, p. 631, 1903).
{ Erlauterung zur Routenkarte der Expedition Steinmann, Hoek, v. Bis-
tran, in den Anden von Bolivien, 1903-4 (Petr. Geogr. Mitteilungen, Heft
1, p. 16, 1906).
I. Bowman—Physiography of the Central Andes. 383
slope on the margin of the great interior basin of Bolivia,
descending to the left in correspondence with the gradient of
the valley of the La Pazriver. In the background is the even-
crested platform, or plateau, whose remarkable topographic
character is only appreciated when one realizes how exceed-
ingly complex is the structure upon which the relatively simple
physiographic outlines are developed. The material of the
right middle distance is soft alluvium, but the material of the
background is metamorphosed sedimentaries, extremely hard
quartzites, sandstones and schists of Silurian, Devonian and
Carboniferous age. An extension to the right of that part of
the sketch which represents the alluvium would bring one to a
smooth-floored basin, the Titicaca-Poopo depression ; a similar
extension, to the right, of the hard rocks of the right back-
Pires Ty
LIMIT OF ALLUVIUM
LIMIT oF ROCK
LA PAZ NALLEY
CITY OF LA PAZ
Fic. 16. Southern portion of La Paz valley from north of the city of La Paz.
ground would lead to the fault scarp which constitutes the
western edge of the eastern plateau. Extended to the left the
sketch would represent the residual masses which constitute a
true mountain chain, the Cordillera Real, and the line of
Nevadas which continue southeast beyond the La Paz valley.
The elevation of the uplifted peneplain is here about 15,000
to 16,000 ft. It continues south and southeast at about this
elevation, and the photograph, fig. 17, shows its development
near the village of Araca, southeast of Llimani. The view
looks northwest and presents with diagrammatic clearness the
physiographic key to the whole region—a baseleveled surface
now uplifted to form a plateau which is surmounted by resid-
ual peaks and ranges. The photograph (fig. 18) represents
similar features along the western base of the Cordillera Real
as seen from the town of Viachi, thirteen miles west of La
Paz. The foreground is alluvium, the residual range is in the
background and in an intermediate position is the rock plat-
form, the now uplifted baselevel of erosion of a former cycle.
3884 LI. Bowman—Physiography of the Central Andes.
From Lake Titicaca the same feature of a plane surface trun-
cating complex structure may be observed. Tig. 19 illustrates
the topographic features displayed north of the lake (west of the
residuals). A similar physiographic development was observed
HAG eles
Fie. 17. View of Illimani and plateau (left) looking northwest from Araca.
inires ike}
Fie. 18. The alti-plano (high plateau) of Bolivia looking east from Viachi.
The Cordillera Real in the background.
—
I. Bowman—Physiography of the Central Andes. 385
as far north as Cuzco, Peru. Photographs of the Cerro de
Pasco region seem to indicate, together with reports upon the
complex structure of the region, an identical history. Con-
sidering the wide range of observations and the excellent
development of the feature of baseleveling, its importance
at once becomes evident. Within the mountainous or residual
mass one has the utmost wildness of mountain form—pinna-
cles, needles and crags developed upon the highly complex
schists and gneisses whose upturned edges are cleaved by the
swift snow-fed streams. The wildness and beauty of the
Pres 19:
Fie. 19. Eastern end of Lake Titicaca, with dissected plateau-remnant in
the background.
scenery are brought out by fig. 20, a photograph representing
Alpine features within the Nevadas de Araca.
To describe each separate locality where the now uplifted
and dissected peneplain was identified, would be essentially
but a repetition of the descriptions already given. Near
Huynuni, 15,500 ft. above sea level and 500 ft. above the tin
mines of that place, a splendid view to the south and southwest
was obtained, and no one could fail to be astonished at the
perfection of its development there. At the Abra Puca-Puca
and Abra de Malaga, northeast of Cochabamba, fig. 21, the
view includes a great sweep of country to the south and south-
east toward Sucre; and as far as the eye can reach the even
sky-line denotes how extensive is the development of the
peneplain in this direction ; while the same great stretch of
886 JL. Bowman—Physiography of the Central Andes.
lofty plateau, scarcely broken by residual ranges of only com-
paratively slight extent, is viewed at 14,000 ft. from the
summit of the pass east of Pretoria Station, on the coach-road
between Oruro and Cochabamba.
Before considering further the physiography of the eastern
Andes, it is well to recall the main facts of the physiography
of the western Andes that are correlated with those of the
eastern Andes. It will be remembered that three cycles of
erosion are found to have oceurred (see Part DI). The first may
be called the great denudation, when a widespread baselevel
of erosion was developed and above which only occasional peaks
and ranges were able to survive because of superior hardness
or advantage of position. Hard and soft rocks, simple and
complex structures, high and low masses, save for the excep-
tions noted, were br ought down to one common level but little
above the sea. This is the great dominating topographic fact of
the region, the organizing principle of the physiography. It
represents a time interval of great length. Marine sediments
younger than the Tertiary are nowhere found in the central
Andine region, except in a very narrow zone near the sea in
northern Chile (Eocene and doubtful Miocene). Elsewhere
only terrestrial deposits occur. Even the Eocene deposits
represent very limited invasions of the sea in the area now
known as the coastal plateau. We have here an old land area
long denuded and brought at last to a baseleveled condition.
What the age of this peneplain is it seems now impossible
to say. It appears from the paleontologic record to have
suffered its chief deformation in the Tertiary, and if this
inference be correct we have between South America and
North America a very striking parallelism of topographic
development.
The uplifts to which the eastern and western Andes are
commonly accredited are thus seen to have little to do with
the present elements of mountain form there displayed. Initial
topographic irregularities responsive to structural conditions
were largely obliterated; and the orogenic movements could
only be said to be physiographically important as they occa-
sionally determined the foci of those residual heights which
survived the great denudation. It must, therefore, be emphati-
cally stated that the central Andes as we know them to- day are
the direct products of orogeny. The parallel ranges now
observed, say between Sucre aud La Paz, are not, in “general,
the axes of first disturbance. They are the pr oducts of revived
erosion acting subsequent to a period in which the initial oro-
graphic features were largely destroyed.
L. Bowman—Physiography of the Central Andes. 387
Fie. 20:
Fic. 20. The Nevadas de Araca, southwest of La Paz.
Fie. 21.
Seale 1:375.000.
Kilometers
Fic. 21. Map of the Cochabamba region (from Steinmann, Petr. Mitth.,
Heft 1, 1906). Disregard scale ratio.
388 TL. Bowman—Physiography of the Central Andes.
Features of the Second and Third Erosion Cycles.
The deformation whereby the peneplain once existing here
was uplifted was epeirogenic in nature, and affected the entire
central Andine region. But the first uplift did not bring the
country to the level at which we now find it. Intermediate
between the present level of erosion and the peneplain we find
another cycle expressed. In it the slopes were in general
developed to the point of maturity, and neither the complete-
ness of development of the peneplain on the one hand, nor the
remarkable activity of erosion in the eastern Andes on the.
other, overshadows the field expression of these mature slopes,
Fic. 22.
Fie. 22.—Graded, waste-cloaked, undissected slopes of maturity near
Colomi, Bolivia, northeast of Cochabamba.
either in areal extent or in perfection of development. A
later and second uplift once more encouraged the dissecting
streams with the result that both the uplifted peneplain of the
first cycle and the mature slopes of the second cycle are fast
disappearing under vigorous stream attack. ‘he most recent
episode in the region is glaciation, which has, in some places,
partially refilled the valleys with alluvium, and softened the
once sharper outlines of the valley forms.
The most striking development of mature slopes observed
was at Colomi (fig. 22) in a mountain valley about half way
I. Bowman—Physiography of the Central Andes. 389
between Sacaba and Inca Corral, about thirty miles northeast
ef Cochabamba. The photograph represents the headwater
section of a small tributary of the Juntas, a river which comn-
bines with the San Antonio to form the Chaparé at the east-
ern base of the Andes. Standing upon the farthest ridge in
the left background and looking still further in the direction
of the view (E), one would see deep dissection and _ partial
obliteration of the mature slopes there developed, because of
the greater rainfall there and greater proximity to the plains
whose low altitude constitute them virtually a baselevel of
erosion. The mature slopes of fig. 22 are preserved because of
greater distance from the plains. The streams beyond the
ridge indicated have a direct course of about fifty miles to the
plains, and the rock in which their courses are cut is soft sand-
stone and shale ; the stream draining the valley of fig. 22 has a
roundabout course fully twice as long, and is held up through-
out the first fifty miles by hard slates and quartzite schists.
An analysis of the slopes of the figure leads one to appreciate
how long an interval of time they represent between the forma-
tion of the peneplain above them and the deep dissection now
elsewhere in progress and soon to be expressed in this valley
also. Geologic structure is here unexpressed to a degree not
less great than in the case of the baseleveled surface above.
The more resistant quartzites and the less resistant slates, and
the most variable dips, are all alike brought to a uniform slope
expression. A heavy sheet of loose waste cloaks the rock
beneath and outcrops are, for the most part, concealed. The
smooth catenary curves of opposite slopes from hilltop to
adjacent hilltop scarcely need description, so well organized do
they appear in the photograph. In fact, organization is the
keynote of the landscape hereabouts. The orderly arrange-
ment of slopes, the continuity of the waste cover, the regular
gradient of streams and valley floors, the complete subjugation
of rocks of varying hardness, all alike attest the perfection of
mature topographic development. Every element thus far
described is contrary to the supposition of but one cycle of
erosion inaugurated by one uplift. These slopes are not pro-
duced by the present drainage ; they are being destroyed by it,
or, as here, are about to be destroyed by it. Only ten miles
down the valley, stream incision is already accomplished and
hastened waste removal is disturbing the delicate organization
of slopes, renewing the rock outcrops and causing the uneven
expression of hard and soft rock. It requires long-continued
erosion at a much less elevation than that at which the region
stands to-day to produce by weathering and stream erosion
such a smooth perfection of maturity. A second profound
uplift inaugurated a third cycle of erosion, the one just begun,
Amy. Jour. Scit.—FourtH Srrizes, Vou. XXVIII, No. 166.—OctTossr, 1909.
~
390 L. Bowman—Physiography of the Centrat Andes.
in which the very heart of the plateau and the residual moun-
tains is being attacked by the torrential streams.
A comparison with the conditions in the Maritime Andes
is important at this pomt to estimate the correspondence of
development there, to reénforce the earlier statement that the
first mountains of the region were all but obliterated, and to
show that broad regional uplift, not orogenic movement, is
responsible for the present loftiness of the central Andine
tableland. Fig. 12 represents the view looking southwest
near the pass at Crucero Alto on the railway tine from Lake
Titicaca to Arequipa in southern Peru. The camera is at
about 14,400 ft. The description applied to the preceding view
could be applied word for word to this view. All elements of
form and structure in the two are comparable, except that the
greater altitude of the camera in the latter photograph brings
the level of the now dissected peneplain into the view and
renders both cycles appreciable at a single glance.
A striking fact is the occurrence of the mature slopes right
up to many of the divides near the western border of the
eastern plateau. This is admirably shown on the coach-road
from Oruro to Cochabamba, where the waste-cloaked valley
heads are thoroughly or wanized with respect to the drainage.
It is only some distance down valley that the dissection
due to the last uplift is topographically expressed.
The disappearance of the slopes of maturity on approach to
the eastern edge of the Andes is not less marked than the
similar disappearance of the even-crested upland in this direc-
tion. Both alike are broken down by the terrific dissection
of the mountain torrents that in many places descend 12,000
and 13,000 ft. in less than 75 miles, or with an average
gradient of over 150 ft. per mile. The mature slopes in their
final expression eastward appear as skeleton shoulders upon
the valley sides, a typical occurrence being on the trail a few
hours’ ride north of Inca Corral.
The most interesting expression of the slopes of maturity is
not, however, their perfect development in regions in which
by virtue of favorable position they are not preserved. It is
their persistent occurrence in localities now undergoing vigor-
ous dissection that gives strongest support to the explanation
based upon three cycles of erosion. Unfortunately, the natural
limitations of a camera did not make it possible to secure a
photograph in which all the elements of form characteristic of
the three cycles were expressed in a single view. T'oo great a
vertical range exists in the position of the three planes of
erosion to make their common expression possible from a single
position. The two localities selected are among a list of at
least a dozen and choice among the list is difticult because of
I. Bowman—Physiography of the Central Andes. 391
the similarity of the views and descriptions. All about
Cochabamba and on the way to the divide toward Oruro, in
the Cliza basin, in southern Peru, between Lake Titicaca and
Cuzco, north of Inca Corral, in each one the same relationship
between slopes exists as may be found in all the others. The
two localities described below, Cliza, and the upper Urubamba
valley in southern Peru, are far thest apart (475 miles in
a straight line), the one in ‘the eastern Andes, the other in the
Bars Andes, and they will therefore serve to show, not only
the: corr espondence of features and development thus far
described, but also the correspondence of development between
the eastern and western Andes.
The Cliza basin lies due southeast of Cochabamba (see map,
fig. 21). It is enclosed by a rim of “cerros”’ or hills and is
drained by the Cliza and Arani rivers, headwater tributaries
Fie. 23.
Fic. 28. Flat-topped spurs on northern border of Cliza basin, Bolivia.
of the Rio Grande, one of the major streams of Bolivia. The
Cochabamba and Cliza basins are alike in consisting of
Devonian sandstones rimmed about by Silurian quartzites and
schists. A deep accumulation of alluvium is found on the
floors of both basins. Both are drained by outlet streams
whose old rock-eut and gravel-strewn terraces several hundred
feet above the present levels of the streams at the narrow
outlets of the basins represent the level of the drainage at the
close of the second cycle of development, during which the
slopes of maturity were formed. These terraces are particularly
well developed five miles west of Arcaji,in the narrow gap
through which the basin waters are discharged. About the
margins of both basins the slopes have the appearance of fig.
23. The sketch is traced from a field drawing made from a
point near the center of the basin looking north by west at the
edge of the surrounding hills, west of the village of San
Benito. Table-topped spurs descend from the broad crest of
the rim (800 to 1500 ft. above the basin floor) by gentle
392 L. Bowman—Physiography of the Central Andes.
gradients ; and all spurs terminate in scarped fronts partially
modified in outline by the huge and widely extended alluvial
fans formed at the mouth of each deep-cut ravine. The flat-
topped appearance of the spurs is very striking indeed and
compels attention in every view from the pass of Puca-Puca
to the Tunari of Cochabamba and about the whole Cliza
basin. The mature profile is easily recognizable, though it is
fast being destroyed by vigorous stream dissection. The
margin of the basin exhibits a progressively greater amount of
dissection with approach to the outlet, where the maximum
incision of the outlet stream is perhaps 150 ft.
Hig. 24.
Fic. 24. Slope relationship in the Urubamba valley near Cuzco, Peru.
The valley of Urubamba, fig. 24, near Cuzco, has features
very closely resembling those of the Cliza and Cochabamba
basins, save for their formation on a much larger scale. The
interstream areas have mountainous instead of spur propor-
tions; the frontal scarps terminating the mature slopes are
nearly two thousand feet high; the ravines are gorges or can-
yons; and the alluvial fans at the canyon mouths are some-
times several miles wide.
A physiographic interpretation of the forms of the eastern
Andes must include attention to the valley and basin filling
which is everywhere so prominent. A period of deep dissec-
tion distinctly below the level of the present drainage was
followed by a period of alluviation, of partial valley filling. In
I. Bowman—Physiography of the Central Andes. 398
spite of the dissection of mature slopes everywhere so prom-
inent, the streams of many of the basins and valleys are not
flowing upon rock but upon alluvium. An episode has occurred
which for a time greatly decreased the dissection of the
lower slopes. That episode is glaciation and its effects are
now expressed by moraines. hanging valleys, striated surfaces,
and valley-head cirques in the mountains; and by alluvium in
the basins and valleys.* At present the streams are actively
removing the alluvium of the valley floors and deeply trench-
ine the alluvial fans of the valley sides. The map of a three-
Hine 25.
>
il,
i
|
\
fl
t
BN
AMILE = 4 INCHES
17°ss'S
Fic. 25. Cliza river and terraces at Cliza, Bolivia.
mile stretch of the Cliza river, fig. 25, likewise shows dissection
by the succession of terraces bordering the basin streams, and
due to the normal sidewise swinging of the river in the down-
cutting accomplished since the glacial period.
fig. 26, shows typical relationships of uppermost peneplain,
lower mature slopes, later dissection, partial valley filling, and
the renewed dissection of post-glacial time, the dissection now
in progress.
* A paper on ‘‘The Glaciation of the Central Andes” will be published
elsewhere at an early date.
The sketch,
394. I. Bowman— Physiography of the Central Andes.
The assignment of a common origin to the now deformed
peneplain of the eastern and western Andes, as expressed in
the discordance between complex structures and flat-topped
plateaus common to both, demands attention to certain parts
of the great interior basin of western Bolivia. This flat-floored
basin was explained (Part I) as primarily the product of a
depressed block of the uplifted peneplain, and its borders as
fault scarps. The time of origin of the basin is established
by reference to the slopes already described. The uplifted
peneplain remnants or the plateau tops terminate abruptly all
about the rim of the basin. Several of the views already
noted (Huynuni, the pass of Apacheta, etc.) are either within
or almost within sight of the western border of the eastern
plateau. This abrupt termination of a well-developed base-
leveled surface indicates that its further extension has been
faulted down, even if more direct evidence of faulting were
not available. We are therefore assured that the basin was
not in existence as an enclosed tract with high bordering scarps
Fic. 26.
a
Fie. 26. Sketch showing three-cycle features prevalent throughout most
of the Central Andes.
at the time that the development of the peneplain was com-
_ pleted, although it may well have existed as a valley or as an
extremely shallow basin. The Mesozoic invasions of the sea
were carried inland to this region, but no marine Tertiary is
found here.
In contrast to the topographic discordance presented at the
rim of the great interior basin is the correspondence of develop-
ment between scarps and bordering basin in the second cycle
of development, which advanced to the point of maturity. Fig.
12, in the Maritime Andes, shows a region which is organized
with respect to the interior basin, and everywhere along the
coach-road from Oruro to La Paz we remarked the thoroughly
subdued slopes of the hills and plateau scarps. Oftentimes the
structure beneath the thin waste cover shows through in
slight corrugations, but in no place has such structure any
important expression in the topography. The slope formed
upon the dip of the schists and slates are scarcely more gentle
or regular than those formed across the outcrooping edges of
the strata. No sudden break either in slope arrangement or
stream gradients marks the debouchure of the main tributary
I, Bowman—Phystography of the Central Andes. 395:
valleys. We are obliged to conclude that the epeirogenic
movement which deformed the peneplain was accompanied by
block-faulting which formed the interior basin and that no
significant amount of further faulting has occurred to mar the
nice relation of slopes and grades which are the product of the
second cycle of erosion. The second uplitt, whereby the third
and present cycle of erosion was inaugurated, is topographically
unexpressed in the interior basin. Its self-contained character,
in common with the great interior basins of all desert regions,
removes it from the immediate effects of uplift. Its floor is a
local baselevel of erosion. Therefore, while expressing the
forms of maturity, it does not represent those of recent dissec-
tion. In fact, we may say that the second cycle of erosion is
here still in progress, the slopes are becoming gentler and flat-
ter, and in the absence of local tectonic movements the cycle
may progress much nearer completion. The formation of a
locally baseleveled area is, however, imperilled by the vigorous
attack of the neighboring streams outside the basin,—the La
Paz, Rio Grande, and Pileomayo. These now head near the
border of the basin and will eventually tap it if existing cond1-
tions of relief and rainfall are indefinitely prolonged.
In the non-glaciated parts, on the eastern border of the
Andes, the slopes are not generally graded in the drainage
systems tributary to the Atlantic. The last uplift was appar-
ently sudden and undoubtedly pronounced and the eastern edge
of the eastern Andes is a well-defined fault scarp 1,000-—4,000
feet in height. The plains at the foot of the scarp are less than
a thousand feet above sealevel. High plateaus and residual
mountains are near low plains and have led to enormous and
rapid dissection. The jaggedness, insecurity, and unorganized
character of the valley and “mountain” forms of this eastern
section are its most conspicuous features below the limit of
glacial action (8,500 ft. more or less). The valleys generally
have a sharp V profile. The exceptions are explained by strue-
tural conditions, in every case examined in detail. Dissection
has not yet advanced to a maximum in the western half of the
eastern plateau, hence in this half the graded and relatively
flat slopes of the previous (second) cycle dominate; in the
eastern section, as a consequence of the great dissection caused
by rapid and great uplift and well-watered slopes, well-defined
hanging lateral valleys occur abundantly below the limit of
glacial action. This is one of the most interesting of the
physiographic results of our work in the eastern Andes. We
had not expected to see the condition at all, to say nothing of
seeing it so generally developed. It was particularly interest-
ing because one rides in a single day from a splendidly
glaciated region with all the “discordant” features diagram-
396 LI. Bowman—Physiography of the Central Andes.
matically developed to a region where the extraordinariiy rapid
normal dissection had produced equivalent discordances, egwiva-
lent but not semelar. The distinctive features of the hanging
valleys of glaciated regions are as unlike those due to normal
but super-vigorous erosion as could possibly be imagined, save
for this one quality of discordant junction of tributary and
master stream. | |
f&, The distribution of these hanging tributaries, indeed in large
measure their very existence, is controlled by geologic struc-
ture. Stream B, fig. 27, is a hanging lateral in the Juntas
Fie. 27. Sketch of hanging valley relationships in the Juntas valley,
Eastern Bolivia.
valley twenty miles within the eastern border of the Andes.
Its small tributaries above X are cut in soft shales. After
running two or three miles or more in the shale belt, they turn
through slate and quartzite of superior hardness which dips
often as steeply as 50°, and occasionally 60°. A waterfall or
a series of waterfalls occurs down the dip of slate or quartzite.
The hanging part of the tributary valley upheld by the thick
layer of highly resistant schist is, in some cases, 1000 to 2000
ft. above the bottom of the main valley. One is scarcely ever
out of sight of one of these in a whole day’s ride. On the
other side of the valley the rapid erosion of the master valley,
itself in a belt of shales, has under-cut the rock so rapidly that
the tributaries are cut off, as Russell has described certain
similar valley tributaries.* Exceedingly complex structure,
strong dip, and sharp alternations of hard and soft rock com-
*Bull. Geol. Soc. Am., vol. xvi, pp. 75-90, 1905.
I. Bowman—Physiography of the Central Andes. 397
bine with rapid uplift and corresponding deep dissection to
make the feature a general one in the eastern Andes region.
The strikingly general occurrence of hanging valleys in this
region constitutes them a type, and hanging valleys cannot
therefore be said to be peculiar to glaciated regions. But it
is the form of the valleys and the geoiogic structure that
with the hanging quality must determine the explanation.
No one could mistake the V-shaped valley at X, fig. 27, fora
glaciated valley. Nor can one find here any equivalent for
the special features of glaciated regions even if the other more
obvious marks of glaciation were removed by post-glacial
stream erosion.
Finally the eastern Andes are, after all, peculiar in the
sense that few regions have the particular combinations of
rapid and great uplift, deep dissection and strong and sudden
alternations of hard and soft rock there exhibited. The regions
in which these conditioning factors are absent do not have hang-
ing valleys except where glaciation has influenced the develop-
ment of slopes. No one should misinterpret these two kinds of
valleys merely because they have this in common, that they
are hanging with respect to the master stream. In the assem-
blage of detailed characters no other likeness between the two
types is discernible.
The foregoing interpretation of the topography of the east-
ern Andes, the great eastern plateau of Bolivia, has peculiarly
interesting support in the drainage relations that are character-
istic of the entire region from Caupolican Bolivia to the south-
eastern border of the Republic at Tarija, the latter region as
described by Hoek.* The drainage is established upon the
surface in curious disregard of the structure. Forty miles
southwest of Tarija, the San Juan and Honda rivers, fig. 28,
flow northwest across the folded Silurian and Cretaceous sand-
stones and Silurian schists in courses that are utterly regardless
of the structure. Even the small Rupasco tributary of the
San Juan, after following a northward course in a synclinal
valley, turns west against the dip of the more resistant
schists and crosses one limb of the next anticlinal before joining
the master stream. The Tarija river itself is represented upon
Steinmann’s mapt as crossing four ridges of rock, varying
from Silurian schists to Cretaceous sandstones, in a distance of
twenty miles. In fact the most striking physiographic feature
of this map is the persistent way in which the drainage cuts
across ridge after ridge of rock of all degrees of hardness, dip,
* Ante.
+ Erliuterung zur Routenkarte der Expedition Steinmann, Hoek, v. Bistram
in der Anden von Boliven, 1903-1904 (Petr. Geogr. Mitteilungen, Heft 1,
1906).
398 TL. Bowman—Physiography of the Central Andes.
and trend. ‘This is especially well-marked in the region north
of Sucre, between Cochabamba and Oruro, where it was observed
by the writer, and again north of Oruro from Caracoilo to Col-
quiri. Any explanation of the drainage must therefore begin
with the larger members of the stream systems directed im
somewhat the same way that they are arranged to-day. The
original drainage produced by the initial folding of the
mountains, a drainage sympathetic with respect to anticlines and
synclines of considerable regularity and great size, has been
completely modified. To-day, not only are the axes of the
major streams everywhere directed across these mountain axes,
Fie. 28.
‘ AN Se =e
4 RES Os
a & . at
. *
B900O 10 |
6F350
rnc Coaa i Mase eS
Fic. 28. Map of the Tojo region, southwest of Tarija, Bolivia. (From
Steinmann, as in fig. 21.) Disregard scale ratio.
but even the tributaries that drain the lesser areas are not
infrequently in anticlinal valleys, though this arrangement is
not general because of the small extent of soft rock found in
the series uncovered by the erosion of the folds.
Identically similar features are expressed in the region north-
east of the Cordillera Real. (Fig. 15.) The streams draining
toward the northeast cut straight across the foot-hill region of
northwest trending ridges, and must likewise have gained
their courses before ridges, as we know them to-day, appeared.
Evans* assigns the stream courses of Caupolican Bolivia to a
remote period “ before the evolution of the present features of
the country ” and the present unsympathetic relation of streams
to structure as being brought about by subsequent “ earth
*Expedition to Caupolican Bolivia, 1901-1902 (Geog. Jour., vol. xxii, 1908).
I, Bowman—Physiography of the Central Andes. 399
movements and erosive action”. We have here the only hint
in the whole literature of a feature as general as it is import-
ant and one which harmonizes so well with the conclusions
reached along other lines that it lends to it a very high
degree of credibility.
The baseleveling of this whole region supplies the condition
which is required “to explain the streams arrangements. The
existence of the peneplain is well established and its existence
meant a high degree of discordance, not only between surface
and structure, but also between drainage lines and mountain
axes. Upon such a baseleveled surface streams flow with a
minimum correspondence between their ultimate courses and
their consequent courses as determined by the initial outlines of
the folds. The warping of a baseleveled surface effects fur-
ther changes, which, as the warping may be entirely inharmo-
nious with respect to the orogenic movements, may still further
disarrange the drainage systems and cause at last an entirely
inharmonious relation between streams and structures. The
warping has the further effect of renewing dissection and by
such renewal exposing the once buried rock to the effects of
differential erosion. The rejuvenated streams begin anew to
carve out mountain range and valley as the dissection of the
softer rock by tributary streams follows upon the transverse
incision of the master streams. There thus comes about pre-
cisely that arrangement of streams that is exhibited in the
eastern plateau to- \-day. Master streams flow regardless of the
mountain ranges, so-called. Some of the smaller tributaries were
developed along belts of weaker rock subsequent to the uplift
of the region; others were developed in harmony with the
original mountain structures.
Perhaps the most interesting drainage feature of the whole
region is the course of the La Paz river, concerning which there
has been a great deal of speculation and an equal amount of
erroneous explanation. Its striking transection of the greatest
mountain chain of Bolivia (fig. 14), its mvasion of the great
interior basin of Bolivia and the soft material in which it is
cutting in the headwater region to-day, have drawn the atten-
tion of every student of Bolivian geography. A widely cur-
rent explanation is that at one time Lake Titicaca dischar ged
eastward through the gorge of the La Paz river, but that this
gorge was blocked by debris from the surrounding mountains,
thus giving an enclosed quality to the Titicaca system. The
explanation would be called absurd, were it not for its advance-
ment by well-known geographers. It is, therefore, necessary
to say that the highest strand line of the old lake that once
existed here is over a thousand feet below the level of the edge
of the basin drained by the La Paz river, and that the lake was
400 L. Bowman—Physiography of the Central Andes.
formed subsequent to the deposition of the alluvium now
found there. There has never been a lake in the region except
this glacial lake, for the deposits which the La Paz river is dis-
secting all about the city are distinctly not lake deposits. They
are the coarsest alluvium, the sort of material that mountain
torrents carry, only roughly sorted and bearing all the marks
of stream and not lake deposition. The clay beds found inter-
calated with these coarse deposits, and used for brick-making, are
glacial clays. They are pebbly, impure, local, and irregular in
occurrence, with nothing in their structure or position to war-
rant the hypothesis of deposition in the waters of a lake. Two
other hypotheses have been put forward in explanation of
the course of the La Paz river. The first is that the river is
antecedent in origin, having gained its course upon an initial
surface previous to the uplift of the Cordillera Real, and that
it, has persisted in it during the slow upheaval of mountains in
its path. Two objections stand in the way of the acceptance
of this view. A stream as short as that part of the La Paz
west of the Cordillera Real (twenty or thirty miles), as Conway
has pointed out,* could scarcely withstand the tremendous
obstacles which these mountains afford. Nevertheless, if the
uplift were slow enough even this great task might be done by
a stream as small as the La Paz. In this event, however, we
should look for one of two results. A stream that has per-
sisted in a given course since the close of the Paleozoic must
have its relations to rock structure and to adjacent divides
well established. We cannot grant to such a stream to-day an
unstable headwater condition. Now it is the most striking
characteristic of the La Paz that its headwater section is under-
going the most vigorous dissection and has been cut back miles
within glacial and post-glacial time. If we restore that part of
its course recently cut away, we have a stream that is even
shorter than the already very short course indicated above ;
in other words, we have a mountain torrent, and it is precisely
this sort of a stream that we conclude that the La Paz must
have been in this region previous to the uplift of the pene-
plain so excellently preserved about the western base of the
Cordillera Real. The tremendous advantages of heavy preci-
pitation and excessive gradients of those streams that flow
eastward off the flanks of the Cordillera Real and the strong
warping in this direction of the old peneplain has given these
streams exceptional advantages over those tributary to the
interior basin. ‘The consequence is not alone expressed in the
La Paz. On Steinmann’s map the Sayacuira is shown crossing
this same mountain axis south of the Sierra Vera Cruz,
although here the height of the range is, to be sure, very much
* Climbing and Exploration in the Bolivian Andes, pp. 126-128, 1901.
I. Bowman—Physiography of the Central Andes. 401
lower than in the path of the La Paz. The Mapiri has eaten
its way back toward Lake Titicaca until now a divide but
1500 ft. high separates it from the Titicaca basin; and in a
geologic sense the capture of the Titicaca waters is imminent
from this direction to a degree but slightly less marked than
in the case of the La Paz. Further interest attaches to these
future changes in the disposition of the basin waters because
of the transition that is now in progress in the Titicaca basin
itself. Its waters are gradually receding from its shores
(fig. 19), and the discharge of the Desaguadero, its outlet, is
likewise decreasing. The climatic change which this expresses
is steadily progressing and, if continued, will lead to the com-
plete isolation of the Titicaca drainage. The lake will then
become salt for a period; but it will again become fresh
when capture from the east or north supplies it again with an
outlet. These changes will occur in a short space of time
geologically speaking, and will wndoubtedly occur if the forces
now in operation here are continued in their present direction.
Further support is given this view by the direction in which
the headwater attack is taking place. The La Paz tributaries
west of the Cordillera Real are all working most vigorously in
the piedmont deposits that front the range. The courses are
arranged in part regardless of the piedmont, in part in strict
contormity to it. The slopes of the piedmont are everywhere
arranged regardless of the main drainage. On the south side
of the La Paz amphitheatre one looks in vain for a slope
towards the amphitheatre. The drainage of the interior basin
begins at the very lip of the amphitheatre and runs away from
it. On the other side the mountain streams descend steeply
from the Cordillera Real and then turn in semi-circular courses
(fio. 14) toward the main axis of the La Paz valley. The
structure lines within the detrital material do not dip down the
present inclines of the valley head, but in a contrary direction.
We must conclude from this evidence that the piedmont was
formed long before the La Paz river headed west of the main
range and that the present course of the river is due to head-
ward gnawing in very recent geologic time, a process still is
active operation.
It is important to note that the rainfall and other conditions
are here very special indeed, and that a similar explanation
cannot be assigned to the other rivers of the plateau whose
courses are out of sympathy with the structure. For example,
the streams that cut across the old mountain axes between
Cochabamba and Oruro are well within the eastern divides
that bar the rain-bearing winds. They occur in a dry region
and, furthermore, one in which the warping of the peneplain
has been distinctly less marked than in the region east of the
402. I. Bowman—Physiography of the Central Andes.
Cordillera Real. They are therefore superposed courses
which were developed upon the old peneplain when what is
now ridge and valley stood at a common level. The uplift
whereby the second cycle of erosion was inaugurated was a
broad uplift, the streams incised their valleys slowly within the
heart of the plateau although on its borders dissection pro-
gressed with extreme rapidity because of the marked break
within short distances between low plain and strongly uplifted
plateau. Only the weaker tributaries have had their courses
moditied. ‘These have developed along the beits of weaker
rock and are arranged in consequence in strikingly linear
courses at right angles to those of the master streams. The
“total-eindruck” is strikingly like that derived from a study
of our own Appalachian drainage system where the trellised
pattern of the drainage bears evidence of the two-cycle origin
of the members of each drainage system.
A striking feature, and one that gives a high degree of con-
clusiveness to the interpretations here offered, is the occurrence
of such large blocks of undissected remnants of the peneplain
at high levels. The reconstruction of an old surface in many
instances depends solely upon the plane of the hill top levels
and its discordance with respect to structure; in the present
case the surface itself, practically undissected over wide areas,
affords a convincing quality to the interpretation. The
relatively slight degree of dissection that the peneplain
remnants of the western Andes display in so many places is
owing in small part to their favorable situation with respect
to the runoff of the mountains (or the lack of lofty moun-
tains) behind them, and in larger part to the extreme aridity
of the climate. The existence of the peneplain, and the slight
extent of residual mountams upon it, led to a much more
even distribution of rainfall than is at present the case. At
no time in their history were the Andes so high as they are
to-day ; and at no time were the regional climatic contrasts
so sharply marked and extreme as they are to-day. These cli-
matic contrasts were offered at the close of the first deformative
period in which the peneplain of the great denudation cycle was
elevated and have been strengthened by the even greater uplift
which closed the second cycle of erosion. Contrasts in degree
of dissection in the cycles since the great denudation have
therefore been gaining in strength, and in the cyele of vigor-
ous dissection recently inaugurated these are at a maximum.
In the western Andes are the relatively undissected plateau
remnants; the eastern Andes show upon their margin some of
the profoundest dissection that can be found upon the earth
to-day.
Geological Department,
Yale University.
T. F. Olcott—New Species of Teleoceras. 403
Arr. XXXVIII.—A New Species of Teleoceras from the
Miocene of Nebraska ; by Tuxropvorn FI. Otcorr.
Teleoceras minor, sp. nov.
Tuts small rhinoceros from the Loup Fork beds of the
Niobrara River Valley, Cherry Co., Nebraska, was found by
me last year and represents the remains of a fully adult but
not old animal. The specimen was broken into several pieces
but is well preserved and consists of the occipital region and
roof of a skull, the right zygomatic arch and maxilla with the
grinders as far as premolar one in place. It shows a very
small but unmistakable rugose spot on the median line of the
frontals, as does TZeleoceras medicornutus Osborn.“ Its
affinities to the genus are recognized in the laterally compressed
-nasals with rounded and protruding tips, the low and broad
occiput, the low sagittal crest and the constricted protocone
and strong crochet on the molars. The premolars are less
reduced than in 7. fossiger. In this respect the type appears
to stand between TZeleoceras and Aphelops with tendency
towards Teleoceras. The alveole of premolar one indicates a
small, short-rooted tooth.
The species is small, the contour of the skull is concave
antro-posterially, the frontal region is flattened, the free nasals
are moderately long with tips protruding 15™" beyond their
inferior borders, which are slightly expanded anteriorly. The
superior dental series is P4 M3. There is a well developed
crochet on all the teeth.
The protocone and hypocone are united in the partly worn
premolars and enclose the median valley. The crochet is prom-
inent on the molars and the antecrochet is strong in molar
one.
Measurements. mm
Length from end of nasals to occipital crest ---.-....-.--- 430 .
Height from lower border of occipital condyle to summit of
SG EIDE SCI Ge a ast eae gen cee CL OE 180
Transverse diameter of occiput including post-tympanic pro-
GEuLES 3 Ree aa ieee Be ie eae a apo yee eee OO)
Greatest transverse diameter of frontals..-....-.....---__ 139
BE mcnmoOnch tovor bite 2s is Je ee Je 568
Memeo Myon ELEC TIASAIS 326 058 28 SO: 21a eye 106
Antro-posterior diameter of molars (crown measurements).. 129
Pmante VOsteriOr diameter PO). = oes le fe Ne ge 31
* Bull. Am. Mus. Nat. Hist., vol. xx, pp. 319-321.
4()4 T. EF. Olcott—New Species of Telcoceras.
Transverse diameter P'2). 2232 oe
Antro-posterior diameter P°3 {225 32. eee
Transverse diameter: 23°) sow, See.
Antro-posterior ‘diameter P4 (2252.2). 222) 22) ae
Transverse diameter°P 4222 22 4.0 a ee
Antro-posterior diameter M1 2-_ 5 252223) 22 32 eee
Transverse diameter MC’ 2.2 (522 2220 Soe
Antiro-postertor-diameter M 2). 2224.) 22528505222 eee
Transverse diameter M2). 0) 3a ee ee
Rockville Center, L. I.
May 3, 1909.
Samuel William Johnson. 405
SAMUEL WILLIAM JOHNSON.
THE prominent chemist and teacher, and the most eminent
figure in American agricultural chemistry, died at his home in
New Haven on July 21st, 1909, in the 80th year of his age.
Professor Johnson was born of Connecticut ancestry a Kings-
boro, N. Y., July 3d, 1830, and spent his youth on his father’s
large and prosperous farm in Deer River, Lewis Co., in the
same state.
His early education was obtained in the common schools
and at Lowville Academy. It was at the latter institution
that he became interested in scientific subjects, and his enthn-
siasm for chemistry led him to equip a laboratory at his home,
where, guided only by his books, ue pursued a systematic
course in analytical chemistry emarkable achieve-
ment for one so young
At this period, when about vy years old, his airst recorded
article, “On Fixing Ammonia,’ was published 7 in the Culte-
vator. This was prophetic of “his future career, and it was
followed in later years by a great many important writings for
the benefit of the farming community.
After having taught for two winters in district schools, Mr.
Johnson, at the age of 18, began his long career in the teach-
ing of science: He taught natural sciences for a year at the
Flushing Institute, Long Island, and two years later he spent
a winter as instructor in the same subjects at the New York
State Normal School at Albany
Meanwhile, in 1850, he had entered the Yale Scientific
School, with which he was soon to be permanently connected,
and studied chemistry, particularly the agricultural branch of
the science, with Professors John P. Norton and Benjamin
Silliman, Jr. During this period of study in New Haven, cov-
ering about eighteen months, he published two mineralogical
notes in this Journal the first of his many publications here,
and also wrote two articles for the Cultivator, the title of one
of them, “ Agricultural Education,” being very significant of
his interests at that time.
In January, 1853, he went to Germany, where he spent two
years in study at Leipsic and Munich with the celebrated
scientists Erdmann, Liebig, von Kobell, and Pettenkofer.
During his stay in Ger many he published i in the Journal fiir
praktische Chemie several articles and notes relating to his
chemical investigations. This work was in pure chemistr V5
rather than on the agricultural side of it, and during his after
life he took a deep interest in the strict science and made
numerous contributions to it.
Leaving Germany early in 1855, he went to England and
Am. Jour, Scl.—FourtH Serizes, Vou. XXVIII, No. 166.—Ocrosperr, 1909.
27
406 Samuel William Johnson.
spent that summer studying with Frankia! During his
stay in Europe he acted as foreign correspondent to the
Country Gentleman, and in that capacity published a large
number of articles on agriculture. It is interesting to notice
that one of the earliest of these letters described the Agricul-
tural Experiment Station at Mockern, for he was destined to
devote much labor towards the establishment of such stations
in the United States, dnd it was chiefly due to his efforts that
this object was finally accomplished, at first in Connecticut.
In September, 1855, having returned to New Haven, he
became chief assistant in the chemical laboratory of the Yale
Scientific School. The next year, 1856, he was advanced to
the position of Professor of Analytical and Agricultural Chem-
istry. In 1874, owing to a modification of his duties, his title
was changed, in what had now become the Sheffield Scientific
School, to Professor of Theoretical and Agricultural Chemis-
try. This position he held until 1896, when he retired as
Professor Emeritus.
Professor Johnson’s long connection with the Scientific
School added much to the fame of that institution. His
career was closely connected with those of Professors Brush
and Brewer, who began their work here at nearly the same
time, when the School was very small. His teaching was
chiefly in the lines of analytical, theoretical, and organic chem-
istry, for the demand for agricultural chemistry among the
students was comparatively small. He always impressed his
students by his wide and profound knowledge, and attracted
them by his sprightly, cheerful disposition. He was a clear,
flnent and philosophical lecturer.
While his teaching and his services to agriculture absorbed
much of his time and attention, Professor Johnson’s chemical
investigations were also important. He was particularly skill-
ful in devising new and improved apparatus and methods of
analysis. In this connection may be mentioned his device for
the accurate determination of carbon dioxide, his simpler sub-
stitute for the original soda-lime used for ‘nitrogen combus-
tions, his apparatus for extraction with volatile solvents, and
his many researches, both alone and with the codperation of
others, on the analytical determination of the important con-
stituents of fertilizers.
His services to agriculture were especially brilliant. Besides
the multitude of more or less popular contributions to agricul-
tural periodicals, he delivered many addresses to farmers,
and as early as 1859 he gave a course of lectures on agricul-
tural chemistry at the Smithsonian Institution. In 1857 he
became chemist to the Connecticut State Agricultural Society,
and for several years published in its Zransacteons the results
of his examination of many fertilizers, and essays upon other
topics.
—
Samuel William Johnson. 407
Shortly after the establishment of the Connecticut Agricul-
tural Experiment Station, for which he had labored so long
and earnestly, he became its Director in 1877, and acted in
that capacity until 1899. In this position he was eminently suc-
cessful, setting an example to the stations of the same kind which
were soon established in. all the other states of the Union.
He was very conspicuous in his literary activity. His
voluminous writings for the agricultural press have been
alluded to already, and his official reports of the Agricultural
Station, published annually for more than twenty years, should
also be mentioned. He edited the first American editions of
Fresenius’s “‘ Qualitative” and “Quantitative Analysis,” and
afterwards revised the former work, supplying it with the
“new system” of chemical nomenclature and symbols. He
published many of the results of his scientific investigations in
this Journal, and was an associate editor of it from 1863 to
1879. Particularly during the earlier years of this period, he
was also a copious contributor to its department of “ Scientific
Intelligence.”
He was the author of several books: ‘“ Peat and its Uses as
a Fertilizer and Fuel,” 1866; ‘“ How Crops Grow,’ 1868;
and “How Orops Feed,’ 1870. One of these particularly,
“How Crops Grow,” a treatise on the chemical composition,
structure and life of the plant, should receive special mention
as a very celebrated work. It was not only received with
much favor in America, but an English edition of it was
published, and it was translated into German, where it was
honored with a preface by Justus von Liebig. It was trans-
lated also into Russian, Swedish, Italian, and Japanese. The
author published a revised and enlarged edition of this work
in 1891. It is fortunate that a full bibliography of Professor
Johnson, up to 1892, was prepared by himself and published
in “ Yale Bibliographies.”
Professor Johnson’s services to science were widely recog-
nized. He was elected to membership in the National
Academy of Sciences in 1866, was president of the American
Chemical Society in 1878, chairman of the sub-section of
Chemistry, American Association for the Advancement of
Science, in 1875, associate Fellow of the American Academy of
Arts and Sciences, and at one time was president of the Asso-
ciation of American Agricultural Colleges and Experiment
Stations. |
Professor Johnson married Elizabeth Erwin, daughter of
George H. Blinn, of Essex, N. Y., on October 13th, 1858.
She and a daughter, Mrs. Thomas B. Osborne, of New Haven,
survive him.
Bs Weis.
408 Scientific Intelligence.
SCIENTIFIC INTELLIGENCE.
I. CHEMISTRY AND PHYSICS.
1. A New-Method jor the Determination of Lodides and Free
Todine.—Buearsky and Hovratna have devised a methed for the
determination of iodine which appears to be particularly well
adapted to mineral waters and similar solutions containing small
quantities of this element. It is based upon the fact that free
iodine is slowly converted into iodic acid by the action of bro-
mine, particularly at about 100°, according to the equation
I, +5Br,+6H,O — 2HIO, + 10HBr.
The liquid to be analyzed is placed in a narrow necked flask of
100° capacity. Not more than 10 or 12 mg. of iodine should be
present. The liquid, if alkaline, is acidified with sulphuric acid
to such an extent that it is finally less than ;1, normal in terms
of free acid. Then about 50° of saturated bromine water are
added, and the flask is filled to the lower part of the neck with
distilled water. The flask is then suspended in a beaker of
water and this water is boiled for one hour. After this opera-
tion the contents of the flask are transferred to a capacious Hrlen-
meyer flask of at least 250°° capacity, a little powdered pumice
stone is added, and the contents of the flask are boiled very vigor-
ously for four or five minutes to remove the bromine. The liquid is
then cooled, 1 or 2 grams of potassium iodide, and sulphuric acid
corresponding to about 10° of the normal solution are added, and
after waiting two or three minutes the iodine set free is titrated
with ;4, normal thiosulphate, using starch solution as an indicator.
One-sixth of the iodine found corresponds to the amount origi-
nally present. Since commercial bromine usually contains a little
iodine, this reagent should be analyzed once for all by the same
method before use.
The authors have obtained extremely good results in carrying
out this method with known amounts of iodine. They have
found that even large amounts of ehlorides and bromides do not
interfere with the method, and also that such impurities as may
be present in natural waters and certain medicines—nitrites,
nitrates, ammonium salts and glucose—do not affect it. Even
compounds of iron and manganese do not interfere if the final
titration is stopped when the blue color first disappears for a
moment.—Zeitschr. anorgan. Chem., \xiii, 184. H. L. W.
2. Uhemical Action of the Penetrating Rays of hadium upon
Water.—It has been shown by M. Krernesavm that the radium
rays which pass through glass act upon distilled water with the
formation of hydrogen peroxide and the liberation of hydrogen,
according to the equation 2H,0 = H,O,+H,. In one experi-
ment where about 0'1 g. of nearly pure radium chloride in a
Chemistry and Physics. 409
sealed glass tube was allowed to act upon 30° of water for forty-
one days, 1t was possible to determine the amount of hydrogen
peroxide by titration with very dilute potassium permanganate.
The hydrogen evolved was collected and measured, and it was
found to be free from oxygen when the experiment was conducted
with the proper precautions for the exclusion of air. The
amount of energy calculated as utilized by the reaction under
consideration as compared with the known amount of heat
evolved by radium was 1 : 17,500 where a thicker tube was used,
and 1: 11,600 with a thinner tube. The author believes that the
effect described is due entirely to the @-rays, and that the y-rays
do not take part in the reaction, for he could not produce the
reaction by the action of the Rontgen rays under similar condi-
tions.— Comptes Rendus, exlix, 116. HG W:
3. The Decomposition of Wuter by Uitra-violet Rays.—A
method for the sterilization of water, consisting In immersing in
it a mercury-vapor lamp acting in a quartz tube for about a
minute, has been described by Courmont and Nogier, who failed
to find in water thus exposed to the ultra-violet light for a period
of ten minutes any evidence of the presence of ozone or other
powerful oxidizing agent. M. Kurnsaum has found, however,
by extending the exposure to ten hours, that hydrogen peroxide
and hydrogen are thus produced, and consequently that the action
of the ultra-violet rays upon water is the same ‘as that of the B
rays from radium.— Comptes Rendus, exlix, 273. HL. W.
4. Radio-uctivity of Potassium Sults—Cam pbell and Mac-
Lellan, who have studied the weak radio-activity of potassium
salts, have attempted to concentrate this property by fractiona-
tion, but always with negative results. Henrior and Vavon,
using the fractional crystallization of the chloride, repeated pre-
cipitation of the chloride with gaseous hydrochloric acid, and
repeated precipitations of barium sulphate in a solution of potas-
sium sulphate, have also failed to find any concentration, and
they have thus strengthened the opinion that this radio-activity is
due to potassium, and not to an unknown impurity. They have
shown also that the radiation in a magnetic field behaves like a
negative flow of electricity, thus identifying it as composed of
B rays.—- Comptes Rendus, exlix, 30. H. L. W.
5. The Cementation of Iron by Charcoal in a Vacuun.—
Conflicting views have prevailed in regard to the possibility of
the absorption of carbon by iron in the absence of gases. GUILLET
and GRIFFITHS have now made some careful experiments in
regard to this matter, and find that when the iron wire and the
sugar-charcoal have been first heated alone in a vacuum to 1000°
C., there is no appreciable cementation when they are heated in
contact to the same temperature. When, however, the materials
are heated under powerful pressure cementation takes place
slowly. They conclude that solid carbon plays an insignificant
part in industrial cementation.— Comptes Rendus, exlix, 125.
H. L. W.
410 Scientifie Intelligence.
mule GEOLOGY.
1. The Devonian Faunas of the Northern Shan States ; by
F. R. Cowrrer Rerp. Mem. Geol. Sury. India, Pal. Indica, n.
ser., II, pp. 183, pls. 20, 1908.—This welcome work on the
Middle Devonian faunas of Burma describes 165 forms from
Padaukpin and 30 from Wetwin. About 120 species are named
specifically and of these 34 are new. Corals, Bryozoa and Brachi-
opoda constitute the bulk of the fossils. The author also reviews
all other Asiatic Devonian faunas. The majority of the species
are clearly western European and of the Calceola sandalina fauna.
There is nothing present to remind one of the Middle Devonian
faunas of eastern North America and but little that recalls our
western faunas having Euro-Asiatic connections. The Wetwin
fossils remind some of the New York Portage biota, but as their
preservation is not good and the fauna a small one, not much
value can be placed on this slight resemblance. Coes
2. Osteology of the Jurassic reptile Camptosaurus, with a
revision of the species of the genus, and descriptions of two new
species ; by Cuartes W. GitmoreE, Proc. U. 8. National Museum,
vol. xxxvi, pp. 197-332, with pls. 6-20 and 48 figures in the
text.—This is an important contribution to our knowledge of
American dinosaurs, to which subject Mr. Gilmore has devoted
especial attention. After a brief historical review of the genus,
Gilmore discusses at some length the osteology of Camptosaurus
as shown mainly in the type specimen of C. brown?, a new species.
The generic detinition follows with an alphabetical list of species.
In the systematic description and revision of species, Gilmore
accepts as valid all four erected by Professor Marsh, to which he
adds two others, one from the Morrison and one from the Lakota.
Of the four European forms referred to this genus the author
admits but one, Camptosaurus prestwichii from the Kimmeridge
clay. Camptosaurus is evidently allied to the European Iguano-
don, but is a more archaic type and suggests a somewhat greater
age for the beds in which it is found. Gilmore thinks that the
evidence shown by the Camptosauride not only supports the
contention that the lower members of the Morrison (Atlanto-
saurus Beds) are below the Wealden, but that they are of greater
age than the Purbeck and possibly equivalent to the Kimme-
ridgian.
‘T'wo restorations of the animals are given, one, that of
Professor Marsh, the other a photograph of a specimen of
Camptosaurus nanus in the American Museum of Natural
History. The former restoration is in error principally in show-
ing too many presacral vertebre, giving the animal too long a
back.
Nothing is said of probable habits, but Mr. Gilmore is of the
opinion that a quadrupedal mode of progression was the more
habitual. B.S, ae
Geology. 411
3. The systematic relationships of certain American Arthro-
dires; by L. Hussaxor, Bull. Amer. Mus. Nat. Hist., vol.
XXvl, pp. 263-272, with pl. xlv, and 8 text figures.—In this
brief paper Dr. Hussakof describes two new genera, each with
- but a single species, and expresses doubt as to the validity of the
genus Protitanichthys of Eastman, the species of which he refers
to the well-known Coccosteus. Re Sy ds
4. A revision of the Entelodontide ; by O. A. PETERSON.
Memoirs of the Carnegie Museum, vol. iv, No. 3, 1909, pp.
41—146, with pls. liv—lxii and 80 text figures.—An admirable piece
of work in which Mr. Peterson has brought together all that has
been published of these swine-like creatures, enriching it with
many observations of his own upon the material at Yale, the
American Museum, the Carnegie Museum, and elsewhere.
The introduction is followed by a revision of genera and
species, followed in turn by a history of the discovery and
excavations in the famous Agate Spring fossil quarries in western
Nebraska; the paper closing with a full anatomical description
of the most notable specimen that these quarries have produced,
the huge Dinohyus, a creature of rhinocerine bulk.
The relationships of the various genera, their distribution in
space and time and an account of the probable feeding habits
close the memoir. The bibliography includes 114 titles, so
extensive is the literature upon this interesting group. RB. Ss. L.
5. A new species of Procamelus from the Upper Miocene of
Montana, with notes upon Procamelus madisonius Douglass ;
by Eart Doverass, Ann. Carnegie Museum, Vol. 5, Nos. 2 and
3, pp. 159-165, with pls. ix-xi and two text figures.—Mr.
Douglass describes briefly the skull, jaws, and cervical vertebre,
constituting the type of the new species of camel, Procamelus
elrodi, found by him in the Lower Madison valley in Montana.
The animal possessed a large skull with a relatively large brain-
case when compared with other species of its genus. The type
skull of Procamelus madisonius, described by Douglass in a
previous paper, is figured for the first time and the description
amplified. R. 8. L.
6. Notes on the fossil mammalian genus Ptilodus with
descriptions of new species; by James W. Gipey, Proc. U. 8.
Nat. Museum, Vol. xxxvi, pp. 611-626, with pl. 70 and 9 text
figures.—In this important paper Mr. Gidley gives some of the
results of a special expedition to the Fort Union beds of S weet
Grass county, Montana. One specimen in particular, the type of
Ptilodus gracilis n. sp., is remarkably complete and adds greatly
to our knowledge of the Allotheria or Multituberculata. Mr.
Gidley’s conclusions may briefly be summed up as follows :
The genus as newly defined combines the upper dentition of
the supposed genus Chirox with the lower dentition of Ptilodus,
thus proving the synonymy of the genera. The same is probably
true of the genera Bolodon aud Plagiolax.
412 Scientific Intelligence.
Certain undoubted Ptilodus jaws from the Fort Union beds
are probably identical with two species of Hallodon described
by Professor Marsh from the Ceratops beds of Converse county,
Wyoming, while other species of Ptilodus have been found in
the Torrejon beds of northern New Mexico, thus giving new
evidence of the close affinity, if not identity, in part at least, of
these three formations. Zodlogically, Mr. Gidley would remove
the Allotheria from the Prototheria, where they have been placed
by certain, authors and associate them with the Diprotodont
Marsupials, not as the direct forebears, but derived from a common ~
ancestry somewhere in Jurassic or Triassic time. Finally Gidley
considers these creatures as frugivorous in habit, possibly living
upon smail fruits and berries. R. 8. L.
7. Descriptions of two new species of Pleistocene ruminants of
the generu Ovibos and Boétherium, with notes on the latter
genus ; by James W. Gipiey, Proc. U. 8. Nat. Museum, Vol.
XXXIV, pp. 681-684, with pls. lvili-lix and one text figure.—Mr.
Gidley here describes two new horned ruminants from post-
glacial deposits, though from widely separated localities, Michigan
and Alaska, the former locality yielding the Bodtherium found
in association with a mastodon.
Gidley expresses the opinion that the genus Boétherium, sup-
posed by some to be synonymous with Ovibos, the musk ox, is
valid and may represent a distinct subfamily of the Bovide.
Rife aes
Ill. Miscertanrgous Screntiric INTELLIGENCE.
1. British Association for the Advancement of Science.—
The seventy-ninth annual meeting of the British Association was
held at Winnipeg during the week beginning August 25. This
is the fourth meeting of the series held outside of the British
Isles ; it was highly successful in attendance and still more in
the importance of the scientific work done, notably the inaugural
address of Sir Joseph Thomson, and the sectional addresses of
Profs. H. E. Armstrong (Chemistry), E. W. Rutherford (Physics)
and Dr. A. Smith Woodward (Geology)—see Sczence for Aug.
27, Sept. 3 et seq., also ature of Aug. 26, Sept. 2, ete. Numer-
ous excursions were held, including one extending to the Pacific
Coast. Dr. T. G. Bonney will be the president of the meeting
for 1910, to be held at Sheffield.
2. Hinfithrung in eine Philosophie des Geisteslebens ; von
Professor Rupotr Eucken in Jena. Pp. 197. Leipzig, 1908
(Quelle & Meyer).
Cyrus Adler, eS OPE ee . tae ee .
a ibrarian U.S. Nat. Museum. .
mwOU XXVilL ahs; NOVEMBER, 1909.
= :
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| AMHRICAN
| JOURNAL OF. SCLENOE,
Epirorn: EDWARD S. DANA.
ASSOCIATE EDITORS
Proressors GEORGE L. GOODALE, JOHN TROWBRIDGE,
W. G. FARLOW anp WM. M. DAVIS, or CAMBRIDGE,
PROFESSORS ADDISON E. VERRILL, HORACE L. WELLS,
L. V. PIRSSON ann H. E. GREGORY, or New Haven,
Proressorn GEORGE F. BARKER, or PHILADELPHIA,
Proressor HENRY S. WILLIAMS, or ItHaca,
Proressor JOSEPH S. AMES, or Battrmore,
Mr. J. S. DILLER, or Wasuinerton.
FOURTH SERIES
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No. 167—-NOVEMBER, 1909.
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al Union ; $6.25 to Canada. Remittances should be made either By money orders, ~
red. pairs, or bank checks (preferably on New York rt
NEW ARRIA
OF
Rare and Choice Minerals,
Adularia, Switzerland ; Apatite, crystal, 2x2, pinkish, Mesa Grande,
Saxony, Connecticut, Tyrol; Alexandrite, Ural Mts.; Argyrodite, Frei-
berg; Apophyllite, Bombay; Arsenopyrite, Freiberg; Amethyst, parallel
growth crystals 2-inch to 6-inch long, Cripple Creek ; Altaite, New Mexico ;
Atacamite, Australia; Bournonite, Nassau, Hungary, England; Boulan-
gerite, Bohemia; Binnite, Binnenthal; Bismuth, Japan; Cerargyrite, Chili, —
Nevada; Chrysoberyl, Finland, Connecticut; Cabrerite, Greece; Cassiter-
ite, Saxony, Bohemia ; Crocoite, Tasmania, Ural Mts.; Chloritoid, Tyrol ;
Carnotite, Telluride, Colorado ; Cerussite, Broken Hill; Cuprite, Arizona ;
Celestite, Bristol ; Calciovolborthite, crystallized, Telluride, Colorado ; Cal-
amine, Ogdensburg; Calaverite, Cripple Creek; Columbite; Conn.; Dia-
monds, loose crystals, Brazil, different forms ; Datolite and Calcite, Bergen
Hill; Eulytite with Bismite, Schneeberg ; Elpidite, Greenland ; Euchroite,
Libethen ; Embolite, Silver City, New Mexico; Emerald, Tyrol, Bogota,
S. A., Ural Mts., N: Carolina; Eudialyte, Greenland ; Erythrite, Saxony ;
Euclase, Capo do Lane, Brazil; Gold, Hungary, crystallized ; Gadolinite,
Sweden; Herrengrundite, Herrengrund ; Haidingerite, Joachimsthal; Her-
derite, Auburn, Poland; Harmotome, Scotland; Iridosmine, Ural Mts.;
Iodyrite, Broken Hill; Ilmenite, Connecticut; Jordanite, Binnenthal ;
Kongsbergite, Norway; Kallilite, Obersdorf; Linnzite, Westfalen; Liv-
ingstonite, Mexico; Lorandite, Maccdonia; Manganite, long erystals, Sax-
ony; Milarite, Switzerland; Mimetite, Freiberg; Monazite, Portland ;
Microlite, Virginia; Meliphanite, Brevig; Neptunite, San Benito; Niccol-
ite, Eisleben; Parisite, Columbia; Pyromorphite, Ems, Cornwall; Phar-
macosiderite, Cornwall, Saxony; Pucherite, Schneeberg; Pyrargyrite,
Mexico, Saxony; Pyrargyrite with tetrahedrite, Nevada; Plattnerite,
Idaho; Pollucite, Paris; Pseudomalachite, Germany ; Phlogopite, Ogdens-
burgh ; Reinite, Japan; Rathite, Binnenthal; Stephanite, St. Andreasberg,
Mexico; Scheelite, Bohemia; Scorodite, Saxony, Cornwall; Smaltite,
Schneeberg ; Sylvanite, Cripple Creek, Transylvania; Stilbite, Bombay ;
Tiemannite, Hartz; Torbernite, Cornwall, Saxony; Tourmaline, Mesa
Grande, Connecticut, Franklin Furnace ; Tetrahedrite, England, Hungary,
Utah ; Uwarowite, Ural Mts.: Uraninite, Portland; Vivianite, Colorado ;
Vanadinite, Kelly, Mexico, Scotland ; Zincite crystals in matrix, Franklin
Furnace ; Zeunerite, Schneeberg ; Zeophyllite, Bohemia ; Anatase, Binnen-
thal; Benitoite, San Benito ; Cobaltite, Cobalt, Ontario; Cinnabar, China,
Spain, Adria; Dioptase, Siberia, Fontainebleau, France; Tellurium,
Cripple Creek.
A. he PETE REL &.
81—83 Fulton Street, New York City.
Plate |.
Am. Jour. Sci., Vol. XXVIII, 1909.
982M
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THE
AMERICAN JOURNAL OF SCIENCE
[FOURTH SERIES. |]
oe
Art. XX X1IX.— Vesuvius: Characteristics and Phenomena
of the present Repose-period ; by Franx A. Perret, K.LC.,
former Honorary Assistant at Royal Vesuvian Observatory.
(With Plate L.)
THe modern eruptive processes of this voleano show a
marked periodicity. Mercalli has published a list of twelve
eruptive periods* since 1700, each culminating in a paroxysm
followed by a distinct interval of complete inactivity, the
duration of which has varied from two to seven years, with
three and a half years as an average. During these periods
of repose the central conduit is obstructed, as a result of the
preceding paroxysm, and the volcano assumes the solfataric
condition marked externally by fumarolic emanations.
It should be noted, however, that if these repose-periods
mark the end of one era of activity, they also herald the dawn
of the next to come. The condition of repose is apparent and
external and represents a preparatory phase which forms a
part of the cycle of events. This should not be considered,
therefore, as an interval of time during which the voleano is
uninteresting, but rather as offering a precious opportunity for
investigating the methods by which the hidden forces develop
into a condition of external activity and for studying at close
range the chemical and other phenomena which may serve as
indices of future eruption.
Owing to the exceptional duration of the last eruptive
period-—1875-1906—and the violence of its culminating par-
oxysm, the present rest-period may be expected to be of greater
than the average length and of more than ordinary interest.
During the three years already elapsed the eruption of Strom-
* G. Mercalli, ‘‘I Vulcani attivi della Terra,” Ulrico Hoepli, Milan.
Am. Jour. Sct.—FourtH SERIES, Vou. XXVIII, No. 167.—Novemper, 1909.
. 28
414 EP. A. Perret— Vesuvius.
boli in 1907 and that of Etna in 1908, together with the Mes-
sina earthquake, have claimed attention, and I have, in addition,
made several visits to the United States; it is therefore with
far less than the desired thoroughness and only as time and
circumstance would permit that I have been able to make
those observations and studies which form the subject matter
of the present paper. |
For the sake of clearness I propose to treat of the character-
istics and phenomena of the volcano during this time under ~
the following heads :— .
1. Morphology. 4. The mud flows.
2. The lavas. 5. The internal avalanches.
3. The fumaroles.
1. It would be interesting to be able to compare at a glance
the external form of Vesuvius as it was at the time of the
last repose-period—1872-1875—with its appearance at pres-
ent; the difference would represent the constructional capacity of
a single eruptive period and would be instructive in showing
how rapidly the old crater basin of Monte Somma is being
filled by the accumulations of lava and fragmentary ejecta.
The slow flows of 1881-8, of 1885-6, 1891-4, 1895-9 and
1903-4 ail formed lava-cupolas of considerable size which,
with the sub-terminal streams on the westerly flank in 1905-6,
form quite a regular distribution around the central cone.
The great cupola of 1895-9 is especially important from a
practical point of view, as showing the encroachment of the
new Vesuvius on that spur of the ancient mountain—the Colle
Canteroni—where stand the Royal Observatory and the Eremo
Hotel. A glance at fig. 4 will show how little remains of that
oasis in the desert of lava, and it would seem not improbable
that one or two more eruptive periods—say sixty years of
time—may suffice to cover the site; unless, indeed, the very
presence of this great lava-mound with its roots shall prove
to have so sealed the approaches in this direction that future
flows here may be of rarer occurrence.
The rapid lateral outflows on the southeast flank during the
last great eruption were not accumulative and did not mate-
rially alter the contour of the mountain although they were
probably responsible for the great- external collapse of the
cone on that side; but the enormous quantity of fragmentary
ejecta has altered the outline of the cone and greatly aided in
the filling up of the Atrio del Cavallo, half obliterating the
lava cupolas of 1891 and 1903 and rounding over the many
little bosses—the so-called “ Montagnelle”—resulting from
these flows.
415
FF. A. Perret— Vesuvius.
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416 EF. A. Perret— Vesuvius.
The eruption left the cone obliquely truncated with the
highest portion at the westerly rim of the crater, where the
mountain is well braced with sills of lava. The lowest points
were a “ V ”-shaped cleft on the rim to the north-northeast—
the “ échanerure” of Lacroix—and the easterly rim, where
the cone is chiefly composed of friable material. Since the
eruption the height on this side has been still further reduced
by landslips, making the north and east the best general
direction from which to obtain a view of the entire crater
rim. Fig. 2 shows the appearance of the cone from this side,
the photograph having been taken from the Oognoli di
Fia..- 4.
Fic. 4. Vesuvius—Colle Umberto, showing encroachment of its lavas on
the Colle Canteroni.
Ottaiano, due northeast of the crater, on Sept. 4, 1908. Since
that time I have photographed the crater rim from the north
in order to show by direct comparison the alterations since
the eruption in the neighborhood of the “ échancrure” (see
ime.) er
The interior of the crater has also changed its form since
the close of the eruption. At that time it might aptly have
béen likened to a funnel, the walls sloping inward at a mod-
erate angle to a central well having almost perpendicular sides
and of such a depth as to render the bottom invisible from
any portion of the crater’s edge. Subsequent downslips have
altered the funnel shape to one more nearly resembling a cup
eas
F. A. Perret— Vesuvius. ALG
the bottom of which is visible from many parts of the rim.
The angle between this floor and the side walls is broken by
many taluses corresponding with canals on the walls which
give direction to the falling materials.
By far the best general view of the interior is obtained
from the lowest portion of the northerly rim, and by fre-
quently visiting this spot with the sun at its greatest north
declination—i. e., in June and July—lI have been able to com-
Kie. 5.
Fic. 5. Comparative views of the crater rim as seen from the north.
pose the photograph reproduced in fig. 1 (Plate I). This
shows the entire southern half of the great crater basin with
the east, south and west walls, the talus at the bottom and a
portion of the crater floor. The average height of the walls
is approximately three hundred meters and the diameter across
the top from left to right—east to west—about seven hundred
and fifty meters. The north to south diameter is somewhat
greater and the northwest -to southeast a little less. The
absence of any standard of comparison renders the picture
disappointing to one who is familiar with the noble propor-
tions of the crater, but a man on the opposite brink would
418 FE’. A. Perret— Vesuvius.
appear in the photograph as a mere speck, quite useless for
the purpose of measurement.
2. The lavas of most interest at present are the sub-terminal
flows of 1905-6 on the west-southwest flank. The accumula-
tions of 1881-3 and 1885-6 have too far cooled down to be
interesting, and the same may be said of those of 1891—4 and
1895-9 (Colle Margherita and Colle Umberto), although these
still exhibit sensible surface temperatures with sheht fumarolic
action.* The most recent lavas—those of the rapid lateral
outflows on the southeast flank during the last eruption—have
cooled rapidly and show high temperatures only at or near
their months of emission, where fumaroles bring hot vapors
from the interior. In comparison with these the sub-terminal
flows of 1905-6 on the west-northwest flank of the cone have
shown a comparatively slow cooling. At a certain point
where the path of ascent crosses one of the streams, Merealli,
in April, 1907 found that lead wires were fused while those
of zine were not, indicating a temperature between 325° and
412° C. In February, 1908 wires of tm were melted but
not those of lead, indicating between 228° and 325°. On
Mareh 5, 1908 my electric pyrometer showed at the same
point 244° and on September 3, 1908 it indicated 140°. On
July 10, 1909 this had fallen to 65° ©. On the main stream,
which is somewhat farther to the south, the lava has greater
depth and showed in July, 1909 a temperature of 175° C.
This is at a point some hundred meters farther down the cone
and is the site of the secondary fumaroles which have shown
sublimations, as recorded in section 3.
There is also a sheet of lava on the north-northeast side of
the cone under the “échanecrure.’ ‘Ihe exact date, omic
emission is somewhat of a mystery, although it was probably
during the early part of the last eruption. As a lava-stream
it is of little importance, being of small volume and forming
a self-arrested cascade of glacier-like appearance, but its out-
flow on this side of the cone was, in my opinion, one of the
causes of the formation of the “ échancrure.” Photographs,
far too numerous for reproduction, have been made of this
and other characteristic details of the volcano in the belief that
they will be useful for comparison in the future and in order
that all features of the present repose-period may be properly
recorded.
3. The fumaroles offer the most important field for investi-
gation during the periods of repose, and it is regrettable
that these have not been systematically observed. It is true
that deposits and sublimates were collected after the erup-
* Mercalli observed the lava of the Colle Umberto still incandescent in
1901, and I was able to char a stick in the crevices as late as 1905.
F. A. Perret— Vesuvius. 419
tion and these have been studied by Lacroix, Johnston-Lavis,
Casoria and others, and I shall not take up this phase of the
subject; but that to which I refer is continued observation at
regular intervals of the temperature and chemical composition
of the exhalations, both of which are so intimately related to the
actual internal condition of the voleano. The little which I
have been able to do in this direction is recorded in this section.
For measuring temperatures I find an electric pyrometer
indispensable, not only on account of its wide range but also
Fig. 6.
Fie. 6. Vesuvius—Corded lava of 1881-8.
because the length of the fire-end permits of its introduction
to the depth of a meter or more in the fumarole.
The chemical investigation naturally divides itself into two
branches, viz. field detection and laboratory analysis. For the
former I use the following reagents, which are easily carried
in a pocket case. Carbon dioxide is detected with limewater
and sulphuretted hydrogen with lead acetate paper. For sul-
phur dioxide (SO,) I have adopted a reagent proposed by the
late Prof. Casoria* consisting of a precipitate formed by mix-
ing together solutions of nitroprussiate of soda and chloride
of zine and adding ferrocyanide of potassium. The three
salts have the following proportions:
* ““Una nuova carta rivelatrice dell’ anidride solforosa,” Eugenio Casoria,
Portici, 1204.
420 I A. Perret— Vesuvius.
Nitroprussiate soda ..: _.-._____ 3 parts
Zine chloride, fused: 2-2) 2-222 — o pais
Ferrocyanide potassium --._-. .-.. 3-4 parts -
The precipitate is of a light yellow color, and is not affected
by light. Spread on filter paper and moistened with dilute
ammonia, it turns to a reddish purple when exposed to SO,,.
It has the great advantage of not being affected by hydro-
chloric or hydrofluoric acids, both of which are so often pres-
ent in fumarolic exhalations.
For the detection of hydrochloric acid a glass rod dipped in
a solution of silver nitrate is exposed to the gases and immersed
in dilute nitric acid, when, if HCl is present, the silver chlor-
ide formed will be precipitated. As an alternative, a strong
solution of ammonia on a glass rod may be exposed to the
gases with the formation of white vapors of ammonium chlor-
‘ide by hydrochloric acid, but the former test is more delicate
and reliable, especially in a strong wind.
For laboratory analyses the gases are collected in expanded
glass tubes, which are then sealed off with a benzine pressure
lamp. It is generally necessary to aspirate the gases through
the collecting tubes and for this a rotary tube-pump may be
employed, but occasionally there is sufficient pressure to drive
the gases through the tubes and through a water-valve at the
farther end, provided the collecting tube is connected to a
funnel placed over the fumarole and banked around with
earth. Bunsen used tubes of tin for insertion in the fumaroles,
but the temperature of some of the present Vesuvius vents
precludes their employment. I have found no difficulty in
using glass provided the tube is bent downward just above the
fumarole, otherwise water condenses above and trickles down
to the hot portion, causing the tube to crack.
In the general investigation of fumaroles it is important
to note that those which develop on lava streams at a distance
from their mouth of exit have no connection with the interior
of the mountain, and cannot, therefore, serve as indicators of
its condition. They are formed in connection with fractures
in the lava stream and have an evanescent existence, which is
doomed to extinction with the progressive cooling of the lava.
These often act, for a time, as true fumaroles, bringing forth
and depositing the volatilized products of the lava stream, but
they soon degenerate into carriers of perfectly neutral hot air,
with which, after rain, is mingled the vapor of water. They
are not, therefore, true fumaroles of the voleano but fumaroles
of the superficial lava stream, and are of the secondary type as
contrasted with those which form in connection with fissures
in the mountain, and which may be expected to rise in temper-
ature with its increasing internal activity.
gen
F. A. Perret— Vesuvius. 491
Secondary fumaroles formed in considerable numbers on the
sub-terminal flows of 1905-6 on the west-northwest flank, the
temperatures of which are recorded in the preceding section.
For some time prior to the spring of 1909 chlorides and sul-
phates were deposited by some of these, but since then the
emanations have been neutral, and the ‘majority have been
remarkable as mere purveyors of heated air. Ever since the
eruption the large amount of water vapor given off by these
re ag:
Fie. 7. Collecting gases from a fumarole at a temperature of 438° C.
fumaroles after rain has produced the appearance by day of an
active lava stream.*
Far different from these are the primary fumaroles on the
northern flank of the cone, which are in communication with
an important system of fissures formed in the mountain side
during the eruption. They have been notable for their fairly
high temperature ever since the eruption, and I have con-
siantly insisted upon their importance. Early in 1908 I found
323° C. at one of these, and commenced a series of compara-
aie observations which has several times been broken off in
consequence of the destruction of the fumaroles by individuals
who make a business of selling the minerals of the voleano.
The largest of the fumaroles has, until recently, remained
intact. On March 5, 1908 the temperature here was 344° C.,
* These vapors exhibit the well-known effect of increased visibility on the
application of a lighted match.
A499 fF. A. Perret— Vesuvius.
and by September 8 this had increased to 485°. These fuma-
roles are acid and water vapor is present in small quantity, but
the high temperature causes its absorption by the atmosphere
without condensation. In March of 1909 I found 420°, but
the pyrometer could not then be introduced at the same point
owing to changes in the fumarole. On June 6 I found 428°,
and on June 14, 438°, which is the highest I have observed.
At this time the fumarole was spoiled for observation, as
described above, and on July 9 the temperature was 430°, and
on July 19 it was 416°—a progressive decrease due to the
choking of the vent. This has begun to clear itself, however,
and the temperature has since risen above 420°. I have com-
menced observations at another opening, which showed on
July 9, 800° and on August 14, 308°. :
The result of these observations shows that if the tempera-
tures in this locality have not recently increased to any great
extent, they are, at all events, not diminishing, and it is inter-
esting and somewhat impressive to see, on this sleeping vol-
cano, gases issuing quietly and almost invisibly at temperatures
above the melting point of lead.
Before the destruction of this fumarole it had enlarged
itself into the form of a grotto, at one end of which there
could be seen an abundant incrustation of a white substance,
evidently consisting of alkaline chlorides, but which were not
of very recent formation. It is here that we most feel the
lack of comparative chemical analyses made at regular inter-
vals of time, but through the kind codperation of Dr. Martin
Henze, of the Zoological Station of Naples, I have, at last,
been enabled to commence a series of investigations along this
line. Gases and deposits were collected here on July 1, 1909,
and the analyses, as made by Dr. Henze, are given herewith:
Water vapor (in small amount)
Hydrochlorie acid | Detected on the spot.
Analysis of gas:
Oxy OC Se eae 18°3 to 18°7 per cent.
INiiro gene eee eee SHOE HO} tO, on
100°0 100°0
Analysis of deposit :
White substance, soluble in water.
Bases: Na, K, Mg with traces of Al, Ca
Acids: HCl, H,SO, a little, HF! traces
Proportion of the substances is in the order given.
F. A. Perret— Vesuvius. 493
As regards the gas we have atmospheric air which, as is
usual in volcanic exhalations, is poor in oxygen. ‘This is read-
ily accounted for by its combination with other substances
within the mountain—especially with H,S in the production
of SO,. In the deposit the presence of magnesium in fair
amount is interesting. Hydrofluoric acid is often found on
Vesuvius.
It was decided to collect and analyze simultaneously with
the above the products of a fumarolic area situated on the
same side but below the cone itself, and less than two hundred
meters from the escarpment of Monte Somma. Fumaroles
appeared here through the sand immediately after the erup-
tion, and, whether due simply to a continued existence of those
on the underlying lavas of 1903-4, or to a revivifying of these
by extension of the fissures on the cone to this poirt, the anal-
ysis of their products would form an interesting comparison
with the above, because of their location at a greater distance
from the central conduit and on a lower level.
Their temperature averages 98° C., and water vapor is
abundant.
Analysis of gas:
HS eee Se 4 percent:
CO, aN BF eects we RNS hs ak 2°08 § 66
Oe Tiles i
Ngee ss _ 74-98
100°00
Analysis of deposit :
Yellowish-white substance, soluble in water.
Bases: Al, Fe, Ca,
Acids : H,SO,, SO,
Sulphur, from decomposition of HS.
At a nearby fumarole we found abundant deposits of realgar.
A veritable battery of fumaroles appeared inside the crater,
just below the western rim, some time after the eruption.
They are inaccessible, but their emanations consist largely of
water vapor which is rendered more or less visible according
to the condition of the atmosphere; and I must here insist
upon the importance of taking this into consideration when
judging of the activity of fumaroles. Reports are often made
of a great increase or decrease in the emanations from day to
day, or even during the same day; but it is evident that,
excepting after rain, the output is fairly constant, and the visi-
ble changes are due to a varying capacity of the air for absorb-
494 FF. A. Perret— Vesuvius.
ing the vapor. A certain variation doés, of course, oceur, and
it so happens that this is in correspondence with the humidity
of the air, for it is when the atmospheric pressure is low that
the vapors escape with greater facility, and this condition also
brings moisture-laden air in which the fumarolic vapors can-
not readily be absorbed. In cold, damp air the vapors con-
dense and are rendered fully visible, while in a warm, dry
atmosphere they are often absorbed without condensation,
although their emission from the voleano may be no less
abundant than in the former case. Some fumaroles with aque-
Fie. 8.
Fig. 8. Vesuvius—A mud-fiow in the Atrio.
ous exhalations are so hot that the vapors are always expanded
and absorbed by the atmosphere without condensation, and I
have reproduced this phenomenon at the Solfatara of Pozzuoli
by artificially heating the orifice of an aqueous fumarole, after
which it was found impossible to effect the condensation of the
vapor by the usual means.
[ have recently found an important fumarole on the south-
east flank of the cone and about one hundred meters below the
crater. This has formed on one of the earlier lava flows of
the last eruption, but it is evidently a true, primary fumarole
although it is not acid at present. The temperature on July 10
was 235° ©. Another which is very interesting is situated
accessibly inside the crater on this side and, witha tempera-
ture of only 160° C., gives hydrochloric acid in considerable
quantity. There is not a trace of SO,,.
F. A. Perret— Vesuvius. 495
~
4. The mud flows, as a destructive post-eruptive phe-
nomenon, have formed a conspicuous feature of the repose-
period. The eruption left the mountain covered with deep
layers of sand in various degrees of fineness mingled with
blocks and bowlders of every description, and, although the dry,
hot avalanches during the paroxysm had carried much of this
material off the cone, this only caused its removal farther down
the mountain and thus nearer to inhabited parts. The rains
which follow an eruption, and those of succeeding rainy seasons,
seep through the sand until a certain consistency is reached, when
Fic. 9.
Fic. 9. Vesuvius—Water erosion on the mud-flows.
the mass begins to flow as a mud stream carrying along the
blocks and bowlders and acquiring considerable velocity. Fol-
lowing the ravines and gullies on the flanks of the mountain,
the ‘‘mud-lava” invades the plains below, causing the destruc-
tion of houses, bridges and, not infrequently, of human life.
The government has constructed, at great expense, a series of
stone dams designed to impede the flows, and these have, on
the whole, served the purpose fairly well. There now remains
comparatively little of this movable material and the flows most
often seen at present are of the self-arresting type, having the
general shape of a glacier. . |
The movement of this material under the varying action of
meteoric waters forms an interesting field for the study of
denudation and drainage, the accumulations on gentle gradients
496 EF. A. Perret— Vesuvius.
showing beautiful erosion effects with arborescent trickle-pat-
terns of great delicacy.*
5. The last eruption left great masses of material in unstable
equilibrium around the inside of the crater’s edge, and from
time to time these were precipitated into the abyss, compress-
ing the air by their fall, and were then ejected as immense
dust-clouds which so perfectly resembled true explosions that
reports of a new eruption were frequently seen in the news-
papers. One of these great downfalls occurred while I was
visiting the United States, and I took occasion to deny the
Hire a0:
Fie. 10. Vesuvius—Effect of a large internal avalanche.
report of an eruption and published an explanation of the
phenomenon in the New York papers.
The downfall of these large masses soon raised the floor of
the crater to a point some three hundred meters below the rim
and subsequent avalanches have formed a series of talus cones
around the circumference of this floor which are constantly
growing and thus reducing the size of the flat, central area.
I use the word “avalanche” instead of “dry slip” or “land-
slide” as it conveys a more adequate idea of the grandeur of the
phenomenon. Slips and slides are continually occurring, but
the descent of a true avalanche in the present crater of Vesuvius
* Compare Jaggar’s ‘‘Experiments illustrating Erosion and Sedimenta-
tion.” Bulletin of the Museum of Comparative Zoology at Harvard College,
vol. xlix, 285, 1908.
F. A. Perret— Vesuvius. 497
forms one of the most impressive sights which can be imagined.
Detachment sometimes takes place silently but more often with
HG lle
Fic. 11. Vesuvius—Descent of an avalanche inside the crater.
a sharp crack. The acceleration is almost equal to that of a
freely falling body, as the crater walls are nearly perpendicular.
Huge bowlders, rebounding from the sills of lava, are projected
——-—_-———.
498 F. A. Perret— Vesuvius.
horizontally and then descend in graceful curves, while the
bulk of the avalanche, enveloped in whirling clouds, falls from
precipice to precipice with the reverberating roar of thunder
until it finally precipitates itself upon a talus at the bottom of
the crater. Then ensues the development of a magnificent
dust-cloud, flaring and torch-like at first, but it soon forms a com
pact cauliflower cloud of exquisite beauty, reminding one irresist-
ibly of the “‘nuées ardentes”.* The motion, both of transla-
Hie. 12.
Fic. 12. Vesuvius— Development of an avalanche on reaching bottom of
crater.
tion and of development, is exceedingly rapid, and the cloud
unfolds and advances with sharply defined contours. It should
be noted that we have here no vapor of water, no high tem-
perature and little, if any, electrical potential—nothing, that is
to say, which could constitute anything like an “emulsion,” and
it would seem that all that is required for producing sharp
outlines in a dust-cloud is sufficiently rapid projection against
an air-cushion. .
The smaller of these avalanches are interesting as showing
more clearly the various phases of their development, the
wind often blowing to one side the lighter dust, where it may
* Lacroix, La Montagne Pelée, Paris, 1904.
EF. A. Perret— Vesuvius. 499
al Rie ats. b
Fic. 13. Vesuvius—Four phases of a small internal avalanche.
Am. Jour. Sct.—Fourtu Series, Vou. XXVIII, No. 167.—Novemser, 1909.
29
430 F. A. Perret— Vesuvius.
be seen ascending near the still falling avalanche and thus
forming two columns moving in opposite directions.
The avalanches have recently become more numerous. This
is due, in my opinion, to increasing tension within the volcano,
which causes the detachment of the materials by producing
slight earth tremors. The northerly half of the crater rim is
being by their means considerably reduced in height and
altered in contour, as has already been shown in the section on
morphology.
On this side of the cone I have recently observed, on a very
small scale, a replica of the great external avalanches which
formed so conspicuous a feature of the last eruption. The
present ones are formed, curiously enough, in connection with
those on the inside of the crater. So sharp is the rim on this
side that when it crumbles a portion of the material, with
possibly a bowlder or two, falls outward instead of inward and
forms the nucleus of the external slide, which is limited by the
small amount of readily movable substances upon the cone at
present.
The sand-spiracles which were numerous at the close of the
eruption, and which Lacroix and others have mentioned, are
still to be seen occasionally. Fine sand is caught up in a
vortex of wind forming a funnel like a miniature tornado, but
generally very narrow throughout its length and perfectly
straight. They have a rapid movement of rotation with a slow
one of translation. I have not yet had the opportunity to
photograph one of them.
As to the future, it goes without saying that the remainder
of the repose-period, be it long or short, will be of even greater
interest than that which is already past. Fumarolic activity
should inerease, earth tremors become stronger and more
frequent, until finally—if the volcanic action follows normal
lines—the magma shall have fused and forced its way upward
in the central conduit to the crater, when a new period of
external activity will be inaugurated. A systematic study of
the signs of its coming would be of great value to the science
of prediction.
In concluding, the writer desires to acknowledge his in-
debtedness to Dr. Martin Henze for the chemical analyses, to
Prof. Mercalli for much valuble information and advice, to
Herr Faerber, of Thos. Cook & Son, for materially facilitating
his excursions on the mountain, and to Professor Jaggar for
revision of the proofs of this manuscript.
Naples, Italy, Aug. 26, 1909.
W. P. Jenney—Great Nevada Meteor of 1894. 481
Art. XL.—The Great Nevada Meteor of 1894; by WattER
P. JENNEY.
Mr. Henry C. Corrine, of San Lorenzo, California, relates
that in the winter of 1893-4 he was living in Candelaria,
Nevada, and witnessed the explosion of a great meteor, which
passed directly over the town, about 10 p. m., Feb. Ist, 1894.
The night was clear and tranquil, and the stars were shining
brightly. The meteor came from the west, exploded with a
blinding flash of light, followed after a short interval by the
sound of the explosion, and finally passed out of sight to the
east. Mr. Cutting does not recall that any one at Candelaria
claimed to have seen the meteor before the flash—the first
notice was the intensely bright hight illuminating the whole
sky.
endclowe is situated on the eastern slope of a high hill
which shut off any view of the meteor, coming as it did from
the west, until it was nearly overhead. Mr. Cutting was in
his house, when there came a terrific explosion so that the
house shook with the air-wave; he thought that a powder
magazine had exploded, and ran out of doors. He states that
he saw a bright light overhead in the star-lht sky, and heard
a roaring sound that reverberated like thunder, but more metal-
lic, which lasted for two to four minutes, dying away in a
vibration like the sound given off by a telegraph wire when
struck. The blinding flash first seen was so intense that the
whole landscape was lighted up, and the sagebrush on hills
several miles distant could be distinctly seen; within houses
with shutters tightly closed, the illumination was so strong
that the most minute objects were visible.
Different observers compared notes respecting the interval
that elapsed between the first flash and the sound of the explo-
sion, and agreed that it was nearly thirty seconds. Assuming
that the explosion took place vertically over the town, this
would place the meteor at the moment of explosion ata height
of six and one-half miles above the surface of the earth. When
Mr. Cutting got out of the house, nearly all of the people in
Candelaria were in the streets; there were 75 to 100 China-
men, living in Chinatown, who were terribly frightened. After
the meteor passed, the Chinamen set off ‘firecrackers to scare
the devil away. some thought that the meteor fell a few
miles to the east, and several parties went out to Summit
Springs in search of it, but it was never found.
Observers at Silver Star* did not note the sound of the
explosion, and the operator at Benton,* when called up by
* Small towns near Candelaria.
432 W. P. Jenney—Great Nevada Meteor of 1894.
telegraph, reported that he heard a faint noise; from all of
which it appears that the explosion was nearly over Candelaria.
The San Francisco Examiner telegraphed the operator at
Candelaria for all the facts about the meteor, and an article on
the subject was printed in the Examiner about February 5th
to 10th, 1894. :
Discussion by the Writer.
Other observers state that, immediately following the flash,
the path of the meteor across the sky was a broad band of
intense brilliant red, stretching from west to east; all the while
the path was blazing with the combustion of material detached
from the meteor in its flight. As the meteor passed on, the
band of light gradually contracted in width, the sides coming
together, and the light fading out until only a waning line of
luminous smoke remained floating in the air for several minutes
before it disappeared. Estimates made of the breadth of this
band forming the track of the meteor vary widely ; some say-
ing it looked to be at least 25 feet wide; others, taking possi-
bly into account the distance it must be away, thought the path
blazed in the sky exceeded 100 feet in breadth, and might have
been greater. Several tell that the meteor itself looked to be
three to five times the diameter of the moon as she appears
when rising.
It is probable that the explosion was caused by the forma-
tion of a thick crust resulting from the oxidation of the metal,
which confined the gases generated in the nucleus—the force
of the explosion dissipating in dust the outer shell. This is
confirmed by the fact that no one saw the meteor break up ;
after the flash it continued its flight in a single path as long as
it conld be seen. :
It should be noted that the meteor in its path, coming from
over the Pacific Ocean, passed to the north of, and paralleled
the Mount Diablo base line, passing north of San Francisco.
This meteor is reported to have been seen, traveling across the
sky far to the south, by people living at that time in Belmont,
Nevada, so that it continued its flight at least fifty miles east
of Candelaria, across the deserts of Nevada. ,
Peculiar interest attaches to the meteor of Candelaria since
it seems probable that the great meteorite of Quinn Canyon,
found in 1908, may be the part of it which reached the earth.
This meteorite was described by the writer in the “ Mining
and Scientific Press” for Jan. 9, 1909, and the chief facts m
regard to it are here repeated.
The meteorite was found in the latter part of August, 1908,
by a prospector in the foothills of the Quinn Canyon range* in
* Called in some maps the Grant Mountains.
W. P. Jenney—Great Nevada Meteor of 1894. 483
Bree ile
Fic. 1.—Quinn Canyon, Nevada, meteorite. Top view, length 44 inches,
breadth 54 inches.
IiMVeig Re
Fic. 2.—Side view; length, 44 inches, height 20 inches.
434 W. P. Jenney—Great Nevada Meteor of 1894.
Nye county, Nevada; it was half buried in the soil. The place
where the meteorite fell is almost uninhabited except for a
few sheep herders; it is situated 90 miles due east of Tonopah,
18 miles north of the Mount Diablo base line, and 100 miles
west of the Utah boundary. |
The mass is roughly oval im snape, as shown in figures 1 and
2; the dimensions are 44.34 inches on the base with a height
of 20 inches; the estimated weight is 4000 lbs. The upper
surface is deeply channeled and pitted and covered with a thin
smooth skin of magnetic oxide which has protected it from
erosion; even the lower buried portion is but little rusted.
The Widmanstitten figures appear on a smooth surface,
when etched, as closely spaced, brilliant lines on a black
ground ; an octahedral structure seems to be shown on portions
of the surface. A partial analysis has shown the presence of
5 to 10 per cent of nickel alloyed with the metallic iron.
The mass has been transported with much labor to Tonopah,
where it is now preserved.* It has been carefully handled, and
except for a few ounces cut off with a cold chisel by the pros-
pector who found it, it is now practically as it fell. A care-
ful inspection of the meteorite before it was removed from the
spot where it was found, led to the conclusion that its fall was
comparatively recent, probably within the last twenty years.
It is with much plausibility connected with the Nevada meteor,
described above, of February 1, 1894, since it was found just
about where the nucleus of the meteor might have been
expected to strike the earth.
Tonopah, Nevada.
* This meteorite has recently been acquired by the Field Museum of
Natural History at Chicago.
Gooch and Gates— Decomposition of Hydrochloric Acid. 485
Arr. XLI.—TZhe Phenomena of the Electrolytic Decomposi-
tion of Hydrochloric Acid; by F. A. Goocw and F. L.
GATES.
[Contributions from the Kent Chemical Laboratory of Yale Univ.—cciv. ]
Accorpine to the prevailing theory of electrolysis, all the
ions of a solution, of whatever nature, are acted upon by the
electric forces and all carr y the current by moving through the
solution. Jf more than one kind of ion is present that kind
which has the lowest deposition voltage is first deposited at the
electrode.
In the decomposition of hydrochloric acid the hydrogen ions
derived from the acid travel to the cathode and are there con-
verted into neutral hydrogen. The chlorine ions move to the
anode, and if the solution is fairly concentrated, are there dis-
charged and converted to neutral chlorine. Under such con-
ditions, the hydroxyl ions of the solvent, water, having a
higher decomposition value than the chlorine ions, take part in
the transfer only to an insignificant extent. As the concentra-
tion falls to the point where the diffusion of the acid in solution
is insufficient to replace the chlorine ions which are removed
from the layer of liquid in contact with the anode, the hy-
droxyl ions of water may take part in the transmission of the
current from the solution to the electrode, and the polarization
rises until in extremely dilute solution it approximates the
decomposition value of water. From strong solutions of
hydrochloric acid the gases evolved are hydrogen at the
cathode and chlorine at the anode, while as the concentration
decreases oxygen from hydroxy] is "evolved in place of chlorine.
LeBlanc has shown experimentally the following decomposi-
tion values for varying concentrations of hydrochloric acid:
Decomposition Value
2 Normal HCl 1:26 volts
4 (4 66 1°34 66
| ee ae
16 6¢ 6¢ es i
== 1°69
According to this theory the transmission of the current
from the solution to the electrode is effected at the highest
dilution primarily by the ions of water, while in the interior
of the solution the current is presumably carried almost
entirely by the ions of the acid.
A recent series of articles by Doumer* contains the
account of experiments in the electrolysis of hydrochloric acid
* Compt. Rend., cxlvi, 687, 897.
436 Gooch and Gates— Decomposition of Hydrochloric Acid.
and certain derived inferences as to the part played by water
in carrying the current of electricity and as to the speed of
transportation of the chlorine and hydrogen ions. In the
experiments first recorded,* an electrode of platmum wire
0°5™" in diameter and 6™ in length was used, and in these
experiments it was found that the volumes of oxygen delivered
free at the anode, by currents rangmg from 0°1203™ to
07134”, continued through intervals of about an hour, bore
to the volumes of hydrogen simultaneously set free at the
cathode a relation changing with the concentration of the solu-
tion. Taking the volume of hydrogen evolved as unity, the
ratios of the volumes of oxygen and hydrogen, expressed
fractionally for varying concentrations, are as follows:
Concentration |
per thousand : 14°5 8°7 5°8 ag) 1°45 (?) 0°72
Ratio of oxygen :
to hydrogen : 0034. 0:068 0°082 0:°120- O:16G > 02212
Similar results were obtained in another experiment in
which a silver anode (of unrecorded dimensions) was employed
to fix the chlorine; but the evolution of oxygen was found to
be relatively greater, the ratio for a concentration of 0°72
parts of hydrochloric acid to 1000 parts of solution being 0-253
as compared with 0-212 obtained under similar conditions with
the platinum anode. [rom the fact that the evelution of
oxygen did not cease, but was rather actually increased under
such conditions, Doumer drew the conclusion that the libera-
tion of oxygen in the electrolysis of hydrochlorie acid cannot
be attributed to the secondary action of chlorine on the water
of the solution, and that there is direct electrolytic decomposi-
tion of water as well as of acid.
In a subsequent articlet the account is given of a similar
experiment, with the silver anode, in which readings of the
gas delivered were taken through twenty consecutive periods
of five minutes-each. It is stated that when a silver anode is
employed for the electrolysis of hydrochloric acid, brown
silver oxide is formed until the deposit of oxide and chloride
upon the anode reaches a thickness which it does not seem
able to exceed, and that thereafter the liberation of oxygen
becomes constant, while the chlorine produced in the electrol-
ysis remains fixed on the anode as silver chloride. The liquid
contains no trace of free chlorine or of oxychlorides when
weak currents are employed. During the first twenty minutes
of preliminary electrolysis, in the experiment recorded, no
note was taken of the volumes of gas liberated. For the first
* Compt. Rend., cxlvi, 329-331. +Compt. Rend., exlvi, 687-690.
Gooch and Gates—Decomposition of Hydrochloric Acid. 437
five periods following the preliminary interval, the volumetric
ratios of oxygen to hydrogen were 0°247, 0°272, 0°285, 0°319.
Thereafter, in the remaining fifteen periods, the oxygen-
hydrogen ratios were nearly constant at an average of 0°332.
Practically the same average ratio (0°331) is recorded for
observations taken under varying conditions of current and
concentrations of hydrochloric acid in water; viz., a current
of 0:0062"" and-0:023"" in a solution of 1:25 to 1000; 0°0213™P
and 0°2502”" in a solution of 5:3 to 1000; 0°0202™? and 0°1003™"
in a solution of 10°7 to 1000; and 0°053*™? in a solution of 55°8
to 1000. The conclusion was therefore drawn that the ratio of
the volumes of oxygen liberated at the anode to the volume of
hydrogen received at the cathode in the electrolysis of hydro-
chloric acid is constant and independent of the intensity of the
current and concentration of the solution ; and, masmuch as a
subsequent experiment with a mercury cathode established a
closely concordant ratio, it was further concluded that the
ratio is, perhaps, also independent of the nature of the anode.
The ratio of the volume of hydrogen equivalent to the
liberated oxygen to the total volume of hydrogen taken as
unity, Doumer calls the “factor of ionization of water,” and
this factor, 0°662 or about %, expresses the view that of the
hydrogen received at the cathode about 3 is derived from
water and $ from hydrochloric acid; and that for every
molecule of hydrochloric acid electrolyzed one molecule
of water must also be electrolyzed, if water is ionized to
+ — + ——
2H and O,—or two molecules, if water is ionized to H or OH.
A still later communication®* deals with velocity of move-
ment of the chlorine and hydrogen ions. Upon the hypothesis
that two-thirds of the current is carried by the ions derived
from water and one-third by the ions derived from hydrochloric
acid, Doumer calculates that the loss of acid should be the same
at both electrodes. This was found to be the case in each of
three experiments made with a silver anode in weak solution
and with a feeble current. Doumer, therefore, summarizes
the results in the statement that (1) the ionization of water
interferes in active fashion in the electrolysis of solutions of
hydrochloric acid, and that (2) the speed of transfer of the ions
H and Cl is practically the same.
The earlier and very elaborate transfer experiments by
Noyes and Sammett lead to precisely the same conclusion
as to the ionic velocities, provided it be assumed that two-
thirds of the current is carried through the solution by ions
derived from water. In these experiments, in which standard-
ized hydrochloric acid was electrolyzed between a_ platinum
* Compt. Rend., cxlvi, 894-896. + Jour. Amer, Chem. Soc., xxiv, 949.
438 Gooch and Gates—Decomposition of Hydrochloric Acid.
eathode and an anode consisting of a silver dise about 3°5™ in
diameter, the current density not exceeding 4°5 milliamperes
to the square centimeter, chlorine was not evolved; but some
oxygen was liberated, and in every case silver chloride formed
a cloud about the anode. The transfer number calculated
from the total amount of silver deposited in the voltameter
and the change in the strength of the acid at the cathode
agreed very closely with the number based upon a comparison
of voltameter indication with the change in the chlorine con-
tent of the anode material, this chlorme content having been
found by determining the fixed silver chloride together with
that precipitable by silver nitrate from the anode liquid. The
titration of the anode liquid for acidity gave, however, utterly
discordant results, owing probably, it is said, to the liberation
of some oxygen at the electrode and the production of a cor-
responding quantity of acid. The transfer number calculated
for chlorine, upon the hypothesis that all the current was car-
ried by the ions of hydrochloric acid, varied somewhat with
the dilution and temperature, but, at 29° for N/20 and N/60
solutions, was on the average 166°6; but if it were assumed,
with Doumer, that one-third of the current passing is applied
to the electrolysis of hydrochloric acid, and one-third of the
entire indication of the voltameter were taken as the measure
of amount of current used solely in the electrolysis of hydro-
chlorie acid, the transfer number for chlorine would become
499°8 and would indicate, as did Doumer’s direct tests of
acidity at the anode and cathode, that the hydrogen and
chlorine ions have the same velocity.
In the work of Noyes and Sammet conditions were adjusted
to restrict as far as possible the evolution of oxygen and
regeneration of acid. In that of Doumer conditions were
arranged to secure the maximum evolution of oxygen; and
Doumer’s inference that one-third of the current is always
utilized in electrolyzing hydrochloric acid rests fundamentally
upon the generalization that the proportion of anode oxygen
to cathode hydrogen is constant and independent of the
strength of current and of the concentration of the solution.
In the work to be described we have further studied the
electrolysis of hydrochloric acid under various conditions. In
the experiments recorded in Table I, A, the apparatus used,
and shown in figure 1, was a Hoffman apparatus provided
with a Hempel leveler, so that the gas measurements might be
made at the atmospheric pressure, and the electrodes were
introduced through rubber stoppers. In other experiments,
detailed in Table I, B, the apparatus was provided with an
anode which consisted either of a silver tiltering crucible fitted
with an asbestos mat or of precipitated silver placed upon
Gooch and Gates—Decomposition of Hydrochloric Acid. 489
the mat of a porcelain filtering crucible, as shown in figure 2.
This apparatus was so adjusted that standardized acid might
be run in from the leveler to replace the anode liquid slowly
FIG 1
RUBBER
CONNECT)
CATHODE,
PLATINUM
PLATE 1x5cm.
a=
rr —
=|
TOH
vV
F\
INcU CM
EMPEL
LEVELLER.
ER
AE OE qa
S\LVER OR
PORCELAIN
FILTEQRANG
CRUCIBLE
RUBBER
CONNECTION.
STOPPE RED TH ISTLE
BE.
G2.
TO S\DE NECK FLAS
AND FILTER PUNP
filtered away to keep the composition of the electrolyte
constant and to collect detached and colloidal silver chloride.
Cur-
Time rent
min. amp.
31 0°085
31 0-080
30 0-080
3() 0-050
{ 0-050
307 0-045
30 0:070
30 0:070
* Nearly N/50.
of anode fresh.
ver crucible.
Taste L.—Anodes of Silver.
C
oncen-
Poten- tration:
tial parts
- volt in 1000
88-89
28-32
83-90
90
95
60-65
62-65
is) ©) (=)
<7 <I <7
w Ww ow
0°36*
0-364
OF fae
Orion
+ Nearly N/100.
Hydro-
gen
em?
A
23°94
22°40
22-44
B
14°9
12°9
20°1
20-2
Ratio of Approximate
Oxygen Area of
Oxygen to Hy- Silver Anode
em? drogen em?
3°44 0°143 1-0
2 COmenONLG es Oil
TS OHOIEY PIUAOS
0-9 0:060 ? ||
0:03 0002 204
3109) 0-186 204]
noue 0:000§ 2094
{ Anode previously used. § Surface
| About 8 grs. of precipitated silver in porcelain. [ Sil-
440 Gooch and Gates—Decomposition of Hydrochloric Acid.
From the results given it is obvious that, under the condi-
tions, oxygen was liberated only when the silver surface open
to attack was small and in no ease attained the proportion
noted by Doumer. Though Doumer states, in regard to his
earlier experiments at least, that no chlorine or oxygen-acid of
chlorine was found in the anode liquid, according to our
experience when oxygen was set free it was always accom-
panied by at least a recognizable amount of chlorine. Silver
oxide in mixture with silver chloride was observed upon the
anode in every experiment, and the formation of the oxide
began as soon as the electrolysis was started. It seems plain
that so long as the anode exposes a large silver surface, open
to easy attack, both oxygen and chlorine attack it. Silver
chloride once attached may remain fixed upon the anode, but
silver oxide is subject to the action of the hydrochloric ‘acid as
well as to that of liberated chlorine, ionized or molecular.
Only when the attackable surface becomes sufticiently limited
does the evolution of oxygen begin, and it was repeatedly
noted that an established evolution of oxygen could be easily
interrupted by disturbing the protecting film upon the anode.
The formation of the easily diffusible colloidal silver chloride
which occurs when the free surface of the silver anode is
restricted and the potential across the electrodes rather high,
can hardly be due to the simple action of chlorine upon silver
since it does not take place when a silver anode surface is
freely exposed. Apparently the production of silver oxide
precedes the formation of the colloidal chloride. According
to our experience, when freshly precipitated silver chloride is
submitted to the action of dilute hydrochloric acid it gradually
becomes more crystalline, and not colloidal, while dilute
hydrochlorie acid acts upon silver oxide to form finely divided
silver chloride, and the formation of cloudy colloidal
silver chloride takes place characteristically when silver oxide
held in platinum gauze is dipped into chlorine water, soluble
silver hypochlorite being, no doubt, formed simultaneously.
So it would seem that the condition under which colloidal
silver chloride is most likely to form in the velectrolysis of
hydrochloric acid exists when silver oxide formed upon the
anode is liable to the attack of chlorine, some silver chloride
being formed in the direct action of chlorine upon silver
oxide, and some by the action of the hydrochloric acid of the
solution upon soluble silver hypochlorite. This, it seems to
us, is probably the action which in every case gave rise to a
cloud of colloidal silver chloride about the anode in the trans-
ference work of Noyes and Sammet* with solutions~ of
chlorides.
* Loe. cit.
Gooch and Gates—Decomposition of Hydrochtoric Acid. 441
In the following experiments the silver anode was protected
by a layer of silver chloride to restrict as far as possible the
surface open to the attack of oxygen. -The anode of silver
wire, 2°27" in diameter and 4°™ long, was first dipped in
melted silver chloride and then made the rapidly rotating
anode in a preliminary electrolysis of fairly strong hydro-
chloriec acid until chlorine was freely evolved. In this way
the anode was made inert excepting at imperfectly covered
points, with the practical effect of very much limiting the
active area and, incidentally, of increasing the current density
i
=
GRADED IN
cM
MOU
TOO
“CATHODE.
fy PLATINUM
WIRE
e
INS HEMPEL
eS LEVELLER
| F\G.3.
for given strengths of current. Not every anode thus pre-
pared was perfect enough to be used through an experiment
without formation of colloidal silver chloride, but some ser-
viceable anodes were thus obtained, and with them the experi-
ments recorded were made. [For these experiments the form
of the apparatus was changed to permit movement of the
electrodes and a corresponding adjustment of potential across
the electrodes for different concentrations. The apparatus is
shown in figure 38. In Table IL are given the results in sum-
mary.
442 Gooch and Gates—Decomposition of Hydrochloric Acid.
Tas.LE I].—Anodes of Silver protected by Silver Chloride.
Concen- Ratio of
Poten- tration: Hydro- Oxygen to
Time Current tial parts in gen Oxygen Hydro-
min. amp. volt 1000 em? em? gen
30 "05 11°38 4°3 14°9 3°6 “249
30 05 12°5 0°86 13°6 4°0 7294
30 °05 12°5 0°43 14°8 5°0 338
30 "10 21°0 0°86 26°1 6°4 "245
30 "10 21°6 0°86 25°5 6°7 PAs
30 "10 21°3 0 86 24°6 8°0 °325
30 "10 20°3 0°43 26°3 8°3 °316
30 “10 21°6 0°43 25 0 8°3 332
30 “15 26°6 4°3 39°7 10°5 "264
30 °15 28°5 0°86 Bd) 11°8 315
30 "15 29°5 0°43 37°9 12°5 °330
In these experiments the ratio of oxygen to hydrogen,
though, within the defined limits, not materially or regularly
affected by variations in the strength of current, the potential
across the electrodes, or the current density, is seen to increase
markedly as the concentration of the solution decreases. Only
at the lowest concentration of 0°43 parts in 1000, and with an
anode of very limited active area, was the average value as
high as that obtained by Doumer. Our results, therefore, are
at variance in this respect with those of Doumer. We find
that the ratio of the volumes of oxygen and hydrogen evolved
in the electrolysis of hydrochloric acid depends directly upon
the concentration of the solution; and further that, at a con-
centration of 0°43 parts in a thousand, Doumer’s ratio is
obtained only when the anode is largely protected from the
action of chlorine as well as oxygen.
This being the case, it is interesting to discover how these
‘results obtained with the protected silver anode may compare
with those obtainable by means of platinum anodes for similar
concentrations of the solution. In the following table are
given the details of experiments made with a spiral of plati-
num wire (0°8™"x5™) used as the anode and solutions of
similar concentration.
It is apparent that for the lower concentrations, 0°86 parts
and 0:43 parts in a thousand, the ratios of the volumes of
oxygen or hydrogen are, in the average, but slightly lower
than those obtained when the protected silver anode is
employed. for the higher concentration, 4:3 parts in a
thousand, the ratio proves to be much lower than that obtained
with the silver anode, possibly because, at the higher
concentration of the acid, the effect of the very much higher
Gooch and Gates—Decomposition of Hydrochloric Acid. 443
TasiE III.— Platinum Anode.
Concen- Ratio of Mean
tration: Oxygen for
Cur- Poten- parts Hydro- Oxy- to each
Time rent N.D-io00_ tial in gen gen Hydro- concen-
min. amp. amp. volt 1000 em? cm? gen tration
Anode area=1°'25¢™?
a0: 0°L0 8°0 4°0 43°0 27°6 2°3 "083 0838
30 0°05 4°0 E2Z0P Se Ac3 14°] 223m 1°63 eee =
a0. O10. --8°0 DOr eine Se ye Oe Se lee lh re
30 0°15 12°0 2BID 5 2 ET OLS yea a) 154
a0 0°05 4°0 13°2 O:86)) 522 4°4 GIS) S iene menage
30 - 0°10 8°0 DAD seer oy 28- 0 Weil a Pair ee
a0 = 0°15 12°0 SKC 0) a ieee ens) SQ 10°6 °268 "266
30. 0°05 4°0 14°0 0°43 14:4 4°8 LOO Rie 2
pa = 0°10 8°0 2ORS 09) eee OO eo SOOO oss
a0 = O15 TPR oat) Sa ar tae 11°9 321 °320
but undeterminable current density upon the silver anode
may be important. The ratios obtained with the platinum
anode are never higher than those got by the use of the
silver anode, and this fact leads reasonably to the use of the
platinum anode in solutions of still lower concentration. For,
though in the experiments described the protected silver anodes
were practically unattackable at the current densities required
for the electrolysis of solutions of the concentration employed,
when the attempt was made to extend the range of experi-
mentation to the electrolysis of solutions of hydrochloric acid
of much lower concentration, it was found that the chloride
coating of the anode became disintegrated. In the study of
solutions of extreme dilution, therefore, it became necessary to
revert to the use of platinum electrodes, and this we have
found to be quite feasible. Table IV gives the details of an
experiment upon a solution of the concentration of 0-048 parts
in 1000, with a spiral anode and cathode of platinum wire
0-8" in diameter and 5 long, and in the apparatus of fig. 3.
The gas evolved at the anode during the first thirty minutes
(A) was measured at intervals of five minutes and recorded as
oxygen, without correction for the possible presence of inter-
mixed chlorine. The experiment was continued similarly for
a period of forty-five minutes (B), at the end of which the
measured anode gas was withdrawn, washed with sodium
hydroxide and measured in a Hempel burette with a conse-
quent diminution in volume amounting to 0°5™* on the
25-4" originally found. At the end of another period (C) of
forty-five minutes the anode gas was again withdrawn, and
444 Gooch and Gates—Decomposition of Hydrochloric Acid.
proved to be free from chlorine by testing with potassium
iodide. So itis probable that the shght diminution found in
washing with sodium hydroxide the anode gas of the first two
runs was due to solubility of oxygen rather than to the pres-
ence of chlorine.
The details of five-minute readings and the finals are given
in the table. .
TasLE 1V.—Anode of Platinum: Area 1:25,
Volume of Solution=330°™2
Concen- Ratio
tration: of
Cur- Poten- parts Hydro- Oxy- Oxygen
Time rent N.Bu.ioo tial in gen gen to
min. amp. amp. volt 1000 em? cm? Hydrogen
Ne ;
Start “O% «; BGA 2 ise 0°043 meena oO. See
5a e095 7°6 875 Yes 3°7 17 Sa ae
10 "105 8°4 87 aoe 4°0 ey Ses
15 "105 8°4 87 Sees 3°9 Wes) pee
20 "105 8°4 87 Bee 4°1 1 Egon
25 ‘100 8°0 86°5 eOee 4°() LF ae
30 "100 8°0 86°5 cece 4°] IF aa
23'8 Ors 433
RB
5 100 8°0 85 Braga 3°9 Ls ores
10 100 8°0 85 erie 4°0 1°6 ay
15 100 8°0 84 Sea 3°7 1°6 ee
20 095 7°6 86 sees 4° ihe) fit
25 105 8°4 87 See 4°0 eg Se
30 LOO 8°0 86 af Se 3°7 ey ae
30 095 7°6 86 Ae 4°0 1°8 eae
40 100 8°0 85 See 3°95 126 Lunes
45 100 8°0 85 Fete 3°7 1°6 ee
34°6 15:1 436
C
5 ‘09 7:2 90 See 3°4 1°6 ae
10 "09 7:2 87 ee 3°6 1°6 Stee
15 ‘09 72) 90 one 3°7 17 eS
20 ‘09 (io 90 See 3°6 lis Ae
25 ‘09 We? 89 one oni 1°6 ies
30 “09 C2 87°5 Beer 3°6 1°6 2 ae
35 -09 72 87 eee 3°5 1°4 Sve
40 ‘085 6°8 87 sane 3°7 1°8 cate
45 "100 8°0 87 meee 4°0 1°6 ee
32°8 14-6 "445
* Uncorrected for chlorine.
+ Uncorrected for chlorine. After washing with NaOH the 20°4°™* of A
and B was reduced to 24:9".
t Proved free from chlorine by KI.
Gooch and Gates— Decomposition of Hydrochloric Acid. 445
In this experiment the ratio of oxygen to hydrogen was
fairly constant throughout the entire period of electrolysis
and higher by about thirty per cent than Doumer’s ratio and the
maximum obtained at the lowest previous concentration of the
solution. It is interesting to note, moreover, that the 91:2°™° of
hydrogen evolved in the two-hour runs is the equivalent of
about 0°276 grm. of hydrochloric acid, or of nearly twenty
times the 0°014 grm. of acid originally contained in the 330™°
_of solution. I all the hydrogen was derived from the primary
electrolysis of hydrochloric acid, an amount of the latter equal
to nearly twenty times that originally present must have been
electrolyzed and regenerated in the course of the experiment.
The details of similar experiments with platinum electrodes
of different areas and in solutions of still lower concentrations
are given in summary in the following table. In A are given
the results obtained at various concentrations with an anode of
small area, while in B are given the results obtained with an
anode surface eighty times as large.
TasLE V.—Anode of Platinum.
Concen- Ratio Mean
_ tration: of for
Cur- Poten- parts Hydro- Oxy- Oxygen each
Time rent NDhoo — tial in gen gen toHy- concen-
min. amp. amp. volt¢ 1000 em? em? drogen tration
A
Anode Area=1°25em3
30 0°05 4°0 23°4 0:172 14°6 Oy CoO meter.
30 0°10 8:0 85°7 Neale 24°2 9°9 "409 °399
30 0°05 4°0 97°2 0°086 1A) 5°0 (AOA pea
30 0°10 8°0 87°3 at ee Giese co) la "468 461
30 0°05 4-0 95°2 0°043 p22 a°4 "4492 "449
30 O59 13-12 93" 7 0°0086 8°6 4°] A477 TF
B
Anode Area=100¢™?-
30 0°10 0°10 - 86°7 0172 24:0 orT 379 pe pe
30 0°05 0°05 95°8 6'086 12°8 5°2 "406 seine
30 0°05 0°05 92°8 0°093 11°6 A*7 “AQ a vena:
30 07031 0°031 95°8 0°0086 8°8 3°7 SAD (Tews tenes
The experiments of each series confirm in a general way the
former evidence tu the effect that the proportion of oxygen
liberated increases as the concentration of the solution decreases.
The highest ratio of oxygen to hydrogen, found at the lowest
concentration, 0°0086 parts in one thousand, and at the high
current intensity, is within five per cent of what it would
be were water the primary and sole electrolyte. A compari-
son of the two series shows that a very large increase
in area of the anode is attended with some _ decrease
Am. Jour. Sci.—Fourts Series, Vou. XXVIII, No. 167.—NovemsBer, 1909.
30
446 Gooch and Gates—Decomposition of Hydrochloric Acid.
in the proportion of oxygen set free; or, in general
terms, an eighty-fold increase in the current density involves,
in the average, a ten per cent increase in the oxygen ratio.
It will be seen that the experimental results of which an
account has been given contravene Doumer’s claim that the
ratio of the volumes of hydrogen and oxygen evolved in the
electrolysis of hydrochloric acid is constant and independent
of the strength of the current and concentration of the solution.
They afford, therefore, no basis for Doumer’s calculation of
equal velocities for the hydrogen and chlorine ions. Nor does
Doumer’s discovery of equal acidity at the electrodes establish
such a relation of velocities; for, if it be assumed that the cur-
rent is carried by the ions of hydrochloric acid we have 166°6,
according to Noyes and Sammet,* for the transfer number of
chlorine at a concentration at which the oxygen-hydrogen ratio
approximates Doumer’s figure, 0°332; and if it be further
assumed that the oxygen evolved is set free by the action of
transferred chlorine ions with simultaneous regeneration of
hydrochloric acid, the condition which produces the evolution
of oxygen corresponding to the oxygen-hydrogen ratio 0°332
must result in the production of equal acidity of the electrode
liquids.
The observed. phenomena afford, therefore, no criterion for
deciding how much of the oxygen liberated in the electrolysis
of hydrochloric acid under any given conditions is transferred
through the liquid and how much is evolved by the action of
transterred chlorine at the anode.
* Loc. cit.
Cockerell—EHocene Fossils from Green River. 447
Art. XLII.—Zocene Fossils from Green River, Wyoming ;
by T. D. A. CockEReE 1.
Pants.
FIRMIANITES gen. nov. (Buettneriacez.)
Rather large globose capsules, with apparently five carpels
(three visible in the type, one side of which is exposed), the
surface smooth.
Firmianites aterrimus sp. nov.
Capsule about 133™™", long and broad, as preserved shining
coal-black, the longitudinal sutures evident, slightly raised
above the general surface.
Hab.—On red shale, in the insect-bearing beds, Green River,
Wyoming. (Eocene.) These fruits closely resemble those of
the living genus /irmiana, found in China and Japan, and
extending i in a single species to Africa. It is not impossible,
perhaps, that they actually belong to that genus, but it is no
doubt much more likely that they represent some allied type
no longer living. Among the described fossil fruits, there
is a distinct resemblance to Apezbopsis, which, however, has
maby more divisions.
An apparently related fruit is Palmocarpon corrugatum
Lesquereux, Tertiary Flora, pl. xi, f. 11. As this has more
than three carpels, it cannot be a palm ; it must be known as
Carpolithes corr ugatus. It is from the Basal Eocene at
Golden, Colorado.
COLEOPTERA: OTIORHYNCHID&.
Syntomostylus (?) fortis n. sp.
Length (excluding rostrum) 103™™; rostrum about 24™™,
robust ; elytra 72" ‘Jong and 3 broad, with seven rows of very
large and Gone punctnr es, becoming small and feeble apically ;
about the middle of the elytra there are about two punctures
to one mm.; eyes elongate; thorax much broader than long,
rugose ; anterior femora moderately swollen; hind femora
slender basally, but apically much swollen, their apices
nearly level with the tip of the abdomen; elytra pointed
apically. The following measurements are in a :
Greatest width of hind femora (near apex)_--- 900°
Breage on rostrum about -.2. 22. 22 282 850:
Ecupumoceye about 222.252 22. ieee 850°
Breadth of” Bye ADOU 2 j5 9 eae hs eee eo Oo
fab.—On red shale of Eocene age, Green River, Wyoming ;
collector unknown. This is much the largest ae the Green
448 Cockerell—Eocene Fossils from Green River.
River weevils. It may or may not be congenerie with Seud
der’s Syntomostylus rudis, which is known from elytra only,
found in Eocene rocks in western Colorado. WS. rudis is a
smaller species (length of elytra 5”), but in the character of
the ridges and punctures, and especially in the acute apex, it
‘Hig. tf. q Bigs?
a e
aeqthteoee
ae
—
poe
cs -*
Syntomostylus fortis. Firmianites aterrimus.
a. snout, 6. elytron, c. hind femur
and base of tibia, d. thorax.
agrees well with S. fortis. (It may be well to note that in
Scudder’s Tertiary Rhynchophorous Coleoptera, p. 50, a wrong
reference to the figure of S. rudis is given; it should be fig.
iO aot ie 23) |
Warren— Pegmatite in the Granite of ‘Quincy, Mass. 449
Arr. XLIII.—Wote on the Occurrence of an Interesting
Pegmatite in the Granite of Quincy, Mass.; by C. H.
WARREN.
Recent operations in the quarry of Follen Bros. on North
Common Hill, Quincy, Mass., have exposed a mass of pegma-
tite of such unusual mineralogic interest that it seems desirable
to publish a brief preliminary notice regarding its main fea-
tures. The occurrence was first brought to the writer’s
attention by Mr. I’. Wesley Fuller, of West Quincy, and sub-
sequently through the courtesy of the owners of the quarry,
Professor Charles Palache of Cambridge and the writer were
enabled to make a study of the mass in place and to secure
abundant material, which is now being studied in detail with
the intention of publishing later more fully regarding it. The
pegmatite was encountered near the southern side of the
quarry about 50 ft. below the surface. It appears to be a
huge schlieren of rudely lenticular shape having a maximum -
thickness of 6 or 7 ft. and a depth and length of about 20 ft.
lis position in the granite is nearly vertical. Another much
smaller mass is said to have been taken out nearby.
The contact between the normai granite and the pegmatite
is marked by a narrow band (2” to 8”) of granite, finer in
texture, poorer in quartz and much richer in hornblende than the
normal granite. It shows a well-marked flow-structure. The
pegmatite as a whole, although quite variable in texture and
composition, still preserves a certain symmetry of structure.
Just within the dark band is a broad zone of rather fine-grained
pegmatite consisting essentially of orthoclase, quartz, riebeckite,
and zgirite. Of these the riebeckite is the most conspicuous
mineral, forming long black crystals suggesting somewhat the
tourmaline of other pegmatites. In this zone is a considerable
amount of graphic-granite, particularly as a narrow band about
the margin. The zone also contains considerable amounts of
fine-grained material, mineralogically similar to the coarser,
scattered irregularly through it. In some parts the pegmatite
passes centrally into masses of quartz a foot or more in thick-
ness. The quartz along its margins contains large prisms of
riebeckite covered with a mantle of egirite and also long
acicular crystals of egirite generally arranged in radial clusters.
Both of these minerals grow into the quartz from the pegmatite
without. ‘Toward what may be considered the main central
portion of the mass the pegmatitic material gives way to a fine-
grained rock, consisting essentially of orthoclase (and albite ),
egirite and quartz. Still nearer the center the egirite-feld-
450 Warren—Pegmatite in the Granite of Quincy, Mass.
spar rock becomes much coarser in grain, at the same time
full of cavities aud so loosely coherent that it may be easily
broken up. The minerals, particularly the egirite, project out
into the open spaces. Quartz is now less abundant than
elsewhere, but it is possible that the cavernous texture is in
part due to the dissolving out of original quartz. The feld-
spars are well formed, about equi-dimensional, and will perhaps
average about the size of a grain of corn, although they vary
from this average considerably in either direction. They
appear to be chiefly orthoclase mantled with a thin cover of
albite: albite also forms in small separate crystals. The
eegirite is dark green in color and in general forms very
irregular, prismatic, often tapering crystals which seem to
consist of an aggregate of slender prisms. Many, however,
exhibit a well-developed prism zone (forms 100, 110), are
often twinned (on 100), and not infrequently attain a length
of several centimeters. Terminal faces occur but are rare
and even on the better crystals are apt to be curiously irregular.
Some of the crystals are deeply pitted by solution. Jn addition
to the minerals named there occurs quite abundantly another
mineral which appears to be the rare fluo-carbonate of lime
and the cerium earths, synchysite, described by Flink from
Greenland, where it occurs with a mineral association similar
to the Quincy occurrence. The synchysite occurs generally in
slender, amber-colored prisms terminated by a basal plane
often truncated by the forms of a hexagonal pyramid or
rhombohedron or both. The prism zone is deeply striated and
has a marked oscillatory development. Zircon erystals are
closely associated with the synchysite and are of frequent
occurrence. Minute erystals of ilmenite and hematite are
occasionally found; also a few minute, black crystals of some
as yet unidentified titanium mineral, and two or three small
erystals strongly resembling scheelite. Quartz crystals are
also found in the pockets. These are more abundant toward
the center, while in and along a line of large central pockets
the quartz crystals are very numerous and attain a large size.
The quartz is in part at least of later age and contains many
inclusions of egirite and secondary hornblende (see later).
The upward extension of this line of large central pockets
presents several features of unusual interest. Here are
found undoubted fragments of the pegmatitic material first
described. Although generally smaller they have been noted
as large as 6 or 8 inches in average diameter and are imbedded
in a compact, beautifully silky, grayish-blue crocidolite.
These pockets also contain great numbers of quartz crystals and
a smaller amount of fluorite, both imbedded in crocidolite,
which in fact practically fills up the otherwise free spaces. A
Warren—Pegmatite in the Granite of Quincy, Mass. 451
considerable amount of some other secondary hornblende
occurs in the form of exceedingly delicate, black needles in
the crocidolite, penetrating the quartz, oral in cavities in
the pegmatite fr agments. The large riebeckite crystals in these
fragments are often partially or almost completely eaten out
and the cavities then formed may contain later formed quartz
and hornblende needles. -On one or more faces of the frag-
ments there is usually found a later growth of quartz which
took the form of a direct addition to the original quartz of
the fragment. The quartz crystals of the pockets vary greatly
in size from exceedingly minute individuals to crystals upwards
of a foot in length and 8 or 4 inches thick. Many of
the smaller erystals are very rich in planes although most
of them are curiously irregular, distorted, their surfaces
covered with etch-pits, or what in other cases resemble growth-
forms. Some crystals have been broken and recemented.
Beside the included needles of black hornblende practically all
of the quartz is crowded with the crocidolite, which gives it a
peculiar bluish color often very attractive. The fluorite has a
dark purple color, is beautifully phosphorescent when heated
and forms generally in distinct octahedral crystals sometimes
an inch or two in diameter. It too has been acted on by
some solvent. All stages of solution may be seen to that in
which only the mold of the crystal remains containing a mass
of fibers originally included in the fluorite. In one large
mass of quartz adjoining the line of pockets several good-
sized masses of granular galena carrying a little sphalerite and
chaleopyrite were found, associated with fluorite and crocid-
olite.
The pegmatite as a whole appears to be a segregation from
the granite characterized by unusual richness (compared |
with the granite ) in certain constituents, notably fluorine, the
rare earths, lead, zinc and probably quartz. ‘The crystallization
seems to have taken place from the margin inward with cer-
tain progressive changes in texture and mineral composition,
the central portions becoming as a result increasingly richer in
silica, fluorine, the rare earths and the egirite molecule. The
central cavities are thought to be chiefly mariolitic in char-
acter, thus allowing a free crystallization. Before the com-
pletion ot the crystallization there appears to have been a
movement in the mass as a whole which resulted in more or
Jess breaking and the formation of fragments found in the
pockets. The flow-structure in the dark marginal band about
the pegmatite bears out this idea of movement, The residual
liquor in the central pockets under the changed physical con-
ditions exerted a solvent action on some, perhaps all of the
minerals already formed, and also effected chemical or molec-
452 Warren—Pegmatite in the Granite of Quincy, Mass.
ular changes which resulted in the formation of the crocid-
olite and hornblende needles. Crystallization went on contem-
poraneously with the above process, although solution seems to
have slightly predominated at the end. Surface waters appar-
ently have had but little effect beyond a little kaolinization
of the feldspar and oxidation of the iron-bearing minerals.
A closely similar pegmatite, except that the central pockets
were lacking, was found about five years ago in the Ballou
quarry, located a short distance to the north of the present
occurrence. In the Ballou quarry, the pegmatite had the form
of a nearly vertical pipe some 2 ft. in diameter and about 50
ft. deep. Many handsome polished blocks were made from
this at the time by Mr. F. Wesley Fuller.
It is believed that a more extended study of these pegmatites
will furnish much valuable information regarding the chem-
ical composition of the minerals of the enclosing granite and
about other problems connected with the interesting riebeck-
ite-eegirite rocks of the Quincy and Blue Hill area.
Laboratory of Mineralogy and Petrology,
Massachusetts Inst. of Technology,
July, 1909.
W. P. White—Melting Point Determination. 453.
Art. XLIV.—JWelting Point Determination; by WaAttTER
io) WHEE
[Inrtropuctory.—The recent great advances in pyrometry, to-
gether with the development of the electric furnace, have
given to many physical and physico-chemical determinations
at high temperatures almost the ease and certainty attainable
at ordinary temperatures. The appropriate special technic,
however, being of very recent development, is not yet gen-
erally familiar; the importance, also, of the whole new and
fertile high-temperature field is still growing in appreciation.
Jt has therefore seemed wise that the methods developed at the
Geophysical Laboratory be published from time to time for
general information, aside from their immediate application
to our own work. In pursuance of this idea, two special papers:
have already been published, treating of furnace construction
and of temperature measurement up to 1600° C.* The present
two papers deal with the application
of such measurements to those Fie. 1.
methods of physico-chemical thermal
analysis which, best known through
their revelations of the constitution
of metallic alloys, are now being
applied with equal success to the
minerals and allied compounds.
The first treats of melting phe-
nomena in general, and its conclu-
sions are not restricted to the high-
temperature field. The second
describes the furnace technic used
to realise the conditions treated in
the first. |
The preéminent value of melting fice. 1. Melting curves. A,
ice as a temperature standard has eae = ane C, beleratel tis
made familiar the great constancy so 7 Degen Mee ignore
of the ideal melting point and its ism and Thermal Properties of
independence of external tempera- the Feldspars.
tures. The great majority of actual
melting point determinations, however, fail to show this ideal
constancy, and display a melting interval, rather than a point.
If the temperature-time curve, A (fig. 1), represents an ideal
* Day and Allen, Phys. Rev., xix, 177,1904; W.P. White, Phys. Rev.,
xxy, 334,1907. Other papers from this laboratory incidentally treat of
methods, but in this respect are largely summarized (as well as supplemented)
by the present papers.
454 W. P. White—Melting Point Determination.
melting under uniform heat supply, with MN as the interval
of constant temperature, the actual result with a substance
melting at high temperature more nearly resembles the oblique
curves B and aC where the temperature intervals RS may be
as much as 60°.
When the melting curve is oblique, there is a much ereater
opportunity for both accidental and systematic errors. In our
own work these have not been serious, considering the high
temperatures concerned, and were for a long time far less
uncertain than the extrapolated temperature scale itself, The
greatest discrepancy in a set of determinations of the same
point has seldom reached 3°.*
But other observers had found much larger and sometimes
confusing irregularities, and had questioned the value of the
thermal (Frankenheim) method of determining melting points ;
moreover, the causes for the obliquity of these melting curves
were in themselves of interest ; and finally, in investigations on
some pyroxenes, a problem ore encountered which called for
much more accurate comparative measurements than we had
been getting. A general investigation was therefore under-
taken of the thermal method of deter mining melting points,
with the twofold object of learning more about the properties
of matter in the vicinity of the melting temperature and of
improving our own technic. As a result, the agreement of
our silicate determinations has been increased about five-fold ai
along with an actual gain in case of experimental manipulation.
An insight into the relations involved has also been obtained |
which has cleared up several questions once very puzzling, and
has pointed the way to a further increase in accuracy whenever
this seems necessary.
A number of substances, organic and inorganic, melting at
temperatures from 0 to 1400°, were examined under various
conditions. Most of these experiments were devised to test
hypotheses and need not now be described in detail. The con-
clusions to which they led will perhaps also gain if presented
in a different order from that of the actual investigation.
To fix the ideas, it may be well to recall at the outset the
general plan of the experimental arrangement used in our
reoular work, to which this article more directly apples. The
substance to be melted is contained in the crucible (fig. 2).
*Tt may make for clearness to emphasize at the outset that the errors con-
sidered in this paper, which the investigation here described sought to
diminish, are errors of 5° or less, occurring in the regular work of this
laboratory upon silicate fusions. With the systematic differences of 100°
to 200° sometimes occurring in the literature, this paper has nothing to do.
+ This improvement has already been illustrated in a paper on Diopside
and its Relations to Calcium and Magnesium Metasilicates, this Journal (4),
xxvii, 4, 1909.
W. P. White—Melting Point Determination. 455
In the middle of the charge is the thermometer, which in our
ease has always been a thermoelement of some kind. This is
sometimes used bare, sometimes surrounded by porcelain and
platinum jackets, as here represented. The crucible is heated
by an electric resistance furnace, for which a storage battery
furnishes a very regular source of heat. An additional control
element, C, indicates the furnace temperature, and also, if
desired, permits of regulating it.
Fie. 2. Sectional view of ordinary melting point apparatus (half size).
C, control element.
It is a familiar fact to workers in this field that freezing
points are often sharper and show much better agreement than
melting points. The reasons for this difference occupy much
of the ‘present paper. One result of it is that freezing point
determinations are generally preferred, and most of the litera-
ture of the subject relates to observations made with falling
furnace temperature. Freezing points, however, are uncertain
or useless in substances where undercooling is marked or
crystallization sluggish. Since this is nearly “always the case
in silicates, the melting point, in spite of its greater experi-
mental difficulty, is the ‘only one used in our silicate work, and
is the point mainly i in view in this paper. The special disad-
vantages of the melting curve would no doubt be lar gely over-
come by stirring, but effective stirring is difficult in many
eases, impossible in the rest, and has never been attempted
here.
456 W. P. White—Melting Point Determination.
The principal causes of oblique melting curves appear to be
the following:
A. Primary, 1. e., inherent in the substance itself.
I. Time lag in the melting process (with ey viscous
substances).
II. The presence of impurities.
B. Secondary, i. e., due to a failure of the apparatus to register
truly the behavior of the substance.
IIf. Inconstant heat supply.
IV. The normal temperature gradient between the outside
and inside of the melting charge.
V. Accidental irregularities in temperature distribution.
VI. Flow of heat along the thermoelement.
VU. Electrical conductivity of the charge (in case the
thermoelement is used bare).
VIII. Inhomogeneity of the thermoelement.
IX. Differentiation of the charge in crystallizing.
X. Radiation through the melting substance.
I. Véscostty.—Day and Allen* discovered that albite and
orthoclase exhibit a sort of hysteresis in their melting, and the
same thing has since been found true of quartz. It is con-
nected with the great viscosity of the melted substance near its
melting point. The change of state takes place gradually, even
at temperatures many degrees (100 or more) above that at which
it will also occur, if time enough is given. Theoretically, this
effect must’ probably be regarded as characteristic of all sub-
stances, though of course it is too small to be perceived in
most. That it might generally be large in silicates, however,
did not at first seem at all unlikely, but such is not the case.
Although considerable portions of a charge of albite or ortho-
clase may remain unmelted after several hours exposure at a
temperature 150° or more above the point where melting begins,
diopside (to take one instance) has been heated three times at
rates varying from 4° to 18° per minute with results agreeing
to 1°. (The distinguishing sign of the presence of this phe-
nomenon is of course the variability of the melting tempera-
ture with the rate of heating.) Hysteresis in melting, there-
fore, is only an occasional cause of obliquity in melting curves.+
ite Impurity.—TVhe effect of impurity in diminishing the
sharpness of melting points is fairly familiar, especially to
organic chemists. But the character of the effect on the tem-
perature-time curve seems to have been little appreciated, and
its Importance and magnitude have often been underestimated.
*Tsomorphism and Thermal Properties of the Feldspars, Publication No.
31, Carnegie Institution of Washington, pp. 50-04; this Journal (4), xix,
pp. 119-125, 1905.
+ If the hysteresis is large, however, the melting point procedure evidently
needs radical modification, See the next article, 1 p. 488.
W. P. White—Melting Point Determination. 457
Tt is, in fact, a direct result of the melting point lowering due
to the impurity, and an expression for it can be derived from
the law of the lowering. This takes a very simple form for
the most common and important case, namely, that in which
the depression of the melting point is proportional to the
amount of impurity. A discussion of this case will serve to
show the usual character of this important effect.
In order to define a melting point curve, two quantities are
necessary, and usually sufficient—the temperature rise (d@) and
the quantity of heat (dQ) required to cause it. Indeed, the true
melting point curve is only the graphic expression of the rela-
dQ
ae hen th
76 When the
temperature rise 1s plotted against time, the time really serves
tion between these two, that is, of the quotient
ae is
BON yen?
however, by definition, the specific heat.* Hence a melting
body as arule is completely accounted for thermally if it is
treated as a body of enormously variable specific heat, and this
is often the simplest and easiest way of dealing with it.
The effect of impurity, then, on the melting curve is its
dQ
dO
case where the melting point lowering is proportional to the
amount of impurity present.
Let the melting point of the perfectly pure substance be
taken as the temperature zero; (the temperatures during melt-
ing will then be negative and will decrease numerically as the
substance becomes hotter.) Let 6, be the lowering of the
melting point in the actual case. The temperature, @,, is then
the temperature at which the impurity present has just suffi-
cient concentration to bring the whole mass of solvent into
fluid condition. Next, let half the solvent be crystallized by
lowering the temperature. The concentration of the impurity
is now double what it was before, and the lowering of tempera-
ture by hypothesis also double, or equal to 20,; similarly, one
third of the solvent will remain liquid at 3@,. Or, if A is the
only as an approximate measure of the added heat.
» which is found as follows for the
effect on the quotient
; : : ie. 1.
fractional part of the solvent left in a liquid form, Aco Gas
This may be written A aoa where K is a constant to be
determined.
aa
ae may, of course, also be so measured as to equal the heat capacity.
As the two are proportional to each other for the same charge, the distinc-
tion is of no importance here.
458 W. PP. White—Melting Point Determination.
Now the rate of absorption of heat by melting, that is, the
dQ valine
portion of 16 required for the melting, is proportional to the
amount melted per unit rise in temperature; that is, propor-
d ; |
» or, say, equal to m » where m is merely the
d A A
d 6 d 6
d A
factor of proportion. But ——
tional to
ann and since the integral:
dA torey SG aa
of Ma gy? that is, the integral of Mas from @, tow, must
equal the latent heat, L, therefore mK is equal to L@,.
Accordingly, if S$ is put for the true specific heat at any tem-
perature, the total virtual, or apparent, specific heat, 2, is
10; ;
3 (Se (1)
for temperatures below and not too far from @,. Through
most of the interval where the equation can be used, § is rela-
tively so small as to be usually negligible and the function
may then be written simply,
L@
senna 2
Soe (2)
The form of the resulting melting curve can now be obtained
by writing = for = and integrating from @, to 0, giving
6 i
[Q] = 6 + 7) (4) (2)
from which Q can be obtained in terms of 6. If (2) instead
of (1) is used,
Qe lhe = .° whence
g= ee
from which @ can be plotted in terms of Q. Here @ is still
measured downward from the true melting point, and Q is
really the amount of heat given out as the body freezes. But
of course this expression gives the form of the curve as well as
any, and is simpler than one with positive temperatures and
heat quantities would be.
Such a curve is the smooth curve of fig. 8. The circles
mark a curve actually observed near 900° in a case where
all other sources of obliquity were practically eliminated.
The recognition of the part played by impurity changes
radically the ordinary conception of melting point phenomena.
W. P. White—Melting Point Determination. 459
Instead of a constant temperature, the observer has to deal
with one varying continually from beginning to end.* The
course of the phenomenon, so far from being independent of
the furnace temperature, follows it closely and registers its
INE, By
Temperature
Heat (= Time approximately)
Fie. 3. Typical melting curve. Points taken from an observed curve
for Na.SO, containing + per cent NaCl. X-—O, melting point depression be-
low pure substance. Smooth curve calculated by formula 8 for the depres-
sion, X-O.. Data page 484.
every fluctuation.—_Some consequences of this point of view
deserve discussion. |
1. The accuracy of the thermal method.—The obliquities of
thermal curves have been cited by several observers as an
evidence of the inaccuracy and untrustworthiness of the ther-
mal method. Rather are they the very sign of its fidelity to
the phenomena. If a method could be devised which gave
perfectly sharp points in ordinary substances, it would by that
very fact be convicted of misrepresenting the facts and of con-
sequent untrustworthiness. And while the method, for in-
stance, of locating the melting temperatures by watching for
changes in the appearance of the charge shows in a way the
gradual progress of the melting, its results are much further
removed from the quantitative. There is no definite connec-
tion between the amount of material melted and the appearance
of the charge to the eye. The thermal method alone at high
*The fact that a melting interval and not a melting point is really in
question has been recognized by some observers, who regularly determine
the upper and lower limits of this interval. It is clear, however, from the
discussion above that the assignment of any lower limitis entirely arbitrary.
460 W. P. White— Melting Point Determination.
temperatures contains the possibility of tracing exactly the
progress of a melting from beginning to end.
2. Variation of the obliquity with temperature.—In accord-
e 2
ance with the familiar formula, A = , the melting point
depression, A, is proportional to the square of the absolute
temperature and therefore (see equation (8) for instance) the
melting curve obliquity must vary in the same way. Hence
the large effect produced at high temperatures by amounts of
impurity which would be quite negligible lower down. Thus,
to take a roughly approximate illustration, -1 per cent of an
impurity of molecular weight 80, say CaF,, dissociated to
double the number of molecules, would by the formula lower
the normal melting point (1392°) of diopside 1°3°, and would
cause an apparent doubling of the specific heat 20° below that,
while if the equation (1) held strictly, the beginning of the
melting would be easily perceptible 50° lower still. A similar
impurity would lower the melting point of ice only ‘05°, and
the doubling of the apparent specific heat would occur within
3° of the melting temperature.
These facts have a direct bearing on the question of the
value of melting poimt determinations in natural minerals.
While the impurities of natural minerals in rare cases run within
a few parts per thousand, they are usually to be reckoned
in percents. But one per cent of impurity may be expected to
lower the melting point from 8° to 10° and extend the dis-
tinetly perceptible melting interval over some 100°. And
silicates with 3 per cent of impurity usually show in most
decided fashion the characteristic behavior of two-component
systems.
3. Experimental determination of the quantity of heat
supplied to the charge.—A quantitative knowledge of the heat
supply is evidently essential to a correct melting curve. The
use of time as a measure of it, which forms the basis of nearly
all the common melting point methods, is recognized as merely
a rough approximation,* and would not have answered at all in
most of the cases here treated. Hence a more accurate method
was employed. It rests on the use of the control element, C,
fig. 2, which allows a determination of the temperature differ-
ence of furnace and charge, on which, and not on the
temperature of either alone, the heat flow directly depends.
This method is more fully treated in the second paper, p. 485.
4, Single melting points.—In most determinations on melt-
ing substances, the melting temperature is the sole object of
*G. K. Burgess, Methods of Obtaining Cooling Curves, Bull. Bur. Stand-
ards, v, 223, 1908; W. Rosenhain, Observations on Recalescence Curves,
Proc. Phys. Soc. London, xxi, 183, 1908.
W. P. White—Melting Point Determination. 461
investigation. This temperature, @, of the formula, is the
upper end of the melting interval, the point X of figs. 3 and 4.
The other characteristics of the curve, the values of the specific
heat, ete., are then, at most, questions of minor interest.
N evertheless, i in such cases the complications due to impurity
are.as 1mportant and as troublesome as anywhere. For in an
impure substance the melting temperature desired is merely
one value of a continually changing magnitude. Before it can
be measured it must first be located on the oblique curve.
But, coming as it does at the top of the melting interval, and
therefore at the end of the melting, it falls where the tempera-
ture changes are most irregular, disturbed and uncertain of
interpretation. The resulting difficulties occupy the rest of
this paper. Meanwhile, a glance at fig. 1 shows the difficulty
which may arise in locating the single melting point.
UL. Varying rate of heat supply.—tn determining the
single melting point of an ideally pure substance, the character
of the heat supply is a matter of indifference so long as it does
not approach zero or infinity. For the exact determination of
the melting curve of an impure substance, the heat supply
must be well known, as has just been seen. For determining
the single melting point of a rather impure substance an inter-
mediate condition obtains. The heat supply need not be
known and need not be constant so long as its variations are
regular. That is, the ‘ break” will show on almost any smooth
eurve. The determination of a melting point with a varying
heat supply, however, often gives rise to a secondary phenom-
enon so striking and so apt to be misleading as to deserve
mention here. This occurs when the furnace rate is kept
nearly constant, as it usually is. As soon as the charge begins
to melt, its temperature rise is checked, so that the continued
advance of the furnace widens the gap between them; thus
the constant rate of the furnace necessarily involves a very
variable rate of heat supply to the charge. The result is to
hurry up the latter end of the melting, apparently increasing
its obliquity. The same happens at the end of a freezing
curve, if such is taken. But the end of a melting curve
is the top, of a freezing curve the bottom; hence the two
kinds of curves are distorted out of all resemblance to
each other, the melting curve appearing more, the freezing
curve less, oblique in the upper part than it really is. The
observer who, attempting to secure constant conditions,
approaches his melting or freezing determinations at the same
rate, and then maintains this rate constant in the furnace, is
likely to go through the critical part of his melting curve five
to ten times as fast as he realizes. If, however, the initial rate
is then adjusted by trial so as to vive satisfactory results at
Am. JOUR. ret natier SERIES, VoL. XXVIII, No. 167.—Novemser, 1909.
462 W.P. White—Melting Point Determination.
the end of the melting, the only disadvantage will be the loss
of time in taking the first part so slowly; and this may some-
times be less objectionable than the remedy—which is, to make
separate observations on the furnace temperature and thus
keep the external temperature gradient constant.
Hear DISTRIBUTION WITHIN THE CHARGE.
The next three causes of obliquity constitute the chief prac-
tical problem in melting point work. They depend upon dif-
ferences of temperature within the charge and could be avoided
if thorough and effective stirring were possible. They are less
detrimental in the determination of freezing than of melting’
points, and are less also in metals whose high thermal conduc- »
tivity 1s in part a substitute for stirring. To them it is due
that, other things being equal, the melting point of a salt usually
cannot be determined quite as accurately as that of a pure
metal or as its own freezing point. They may, however, be
greatly diminished by proper experimental arrangements.
IV. Lhe regular and normal temperature gradient across
the charge.—The error and uncertainty resulting from the fail-
ure to stir has often been greatly overestimated. The charge
as a whole may present great temperature differences, but the
thermoelement does not record all these at once. It accounts
only for the portion immediately surrounding it, and when this
portion melts it will show a “ break ” in the temperature curve.
Toward this small system of element and surrounding material,
the outer portions of the charge act in many respects as so
much foreign matter—though foreign matter which is particu-
larly troublesome, on account of its own heat absorptions.
Their effect can be investigated with quite enough exactness
for the present purpose, by the device already used, of treating
the melting charge as a body of variable specific heat.
1. Hxpression for the temperature distribution im an
ordinary charge.—As a heated charge is brought toward its
melting point, the supply of heat is usually constant, and then
= soon becomes the same at all
points. The resulting temperature distribution at any instant
may then be found to a sutticiently close approximation as
follows: Suppose, first, that the body is spherical with a radius
equal to R, and the heat flow is entirely along radial lines.
Consider a spherical surface, A, at a distance, 7, from the center
the rate of temperature rise,
: 4nr°
of the sphere. Its area is 477’; the inclosed volume = The
flow of heat across it may be expressed in two ways: (1)
Directly, as the product of area, conductivity and tempera-
W. P. White—Melting Point Determination. 463
dé
ture gradient, that is, as equal to 47°K ies and (2) as the
heat absorbed by the inclosed volume, or the product of volume,
volume specitic heat, and the rate of temperature rise,
4nr* dé
equal to.-_— S—— i
10
cae these two and integrating, remembering that a
is here a constant, we have
R S dé 2 2 =<
Be: Broke ve R*—7’) (5)
Tf the charge is an infinitely long cylinder, we have the same
expression with 4 substituted for 6 in the denominator of the
second member. In general, we may say, therefore, that the
temperature gradient within a uniform, solid, steadily heated
charge approximates a parabola, and the difference of tem-
perature between center and outside for bodies of the same
shape is proportional to the jirst power of the rate of heating
and to the square of the diameter.
If we let 60 =A@, then 6¢ is the time required for a given
temperature value to pass from RK to 7,—that is, it is the time
lag of r behind R. It equals
S eae
ae (R-") (6)
It is independent of the rate and is thus important as a prop-
er ‘y of the charge alone.
9. Lifect of the melting on the temperature distribution.—
ce an actual melting point determination one fundamental
hypothesis of the preceding no longer holds. The tempera-
ture rise of the charge is not regular ‘after melting begins. We
may, however, still proceed for the case of a small charge, for
which the time required to reach an equilibrium temperature
distribution will be relatively small, so that the divergence
from such a distribution may be neglected in making the first
approximation. Mathematically, the problem then reduces
simply to finding the effect of a change in the specific heat,
the rate of heat supply, a , remaining constant. This is easily
done as follows: Since
dQ = Sdé
AS) Pree
di ae Ss (7)
464 W. P. White—Melting Point Determination.
If, therefore, the specific heat S increases n times, becoming
nS, the rate, = will evidently diminish n times. The time
lag (equation (6)) will znerease n times. The temperature dis-
tribution can be found by substituting from (7) in (5). The
result is:
Aé] d d
199 come = 22 2 gy
In this expression the specific heat does not appear at all. The
equilibrium temperature distribution, therefore, is not altered
by a change in the specific heat. Among these results of a
change in specific heat the increase of the time lag is of most
immediate interest. Occurring under constant heat supply to
the whole charge, it involves a “retardation in the supply to the
center, and one which is proportional to the square of the
radius. The formule thus express in a roughly quantitative
way the otherwise obvious fact that as the melting begins the
inner layers fall behind, since the outer layers for a time absorb
large quantities of heat, passing very little to the interior.
Expressed in terms of temperature, the retardation will be
m—1 times the (original) time-lag times the rate.
This result, however, as already indicated, applies strictly
only to an infinitesimal charge, since it assumes a complete
homogeneity, which the melting itself destroys. In the actual
case, while the body is melting the outer layers will have a
higher temperature and therefore a greater specific heat than
the inner. This, it can readily be shown, will diminish the
temperature difference between center and surface and there-
fore the time lag, while an increase of conductivity due to
melting will probably act in the same direction. The retarda-
tion of the center will thus really increase less rapidly than the
square of the radius, and for a very large crucible will not
even approach the formulee just given.
As soon as the outward layer of the charge is fully melted,
the whole course of the phenomena changes. The virtual
specific heat of the substance while melting is usually from 50
to 100 times what it is before or after, hence the heat capacity
of the whole depends for a time almost entirely on the still
unmelted core. As this diminishes the relative heat supply to
it increases, increasing the obliquity of the critical end-portion
of the curve. Nor is the resulting distortion, like that from
uneven heat supply, above described (page 461), merely a
general increase in steepness at the end. It is a rapidly accel-
erated increase, changing the form of the curve in that region.
In large crucibles, it often masks entirely the break at the end
of the melting, substituting for ita premature break a degree
W. P. White—Melting Point Determination. 465
or two lower down, due to the rapid increase in heat supply
before the melted layer has touched the thermoelement at all.
In brief, then, the inevitable heat distribution in an unstirred
charge has this effect on the center, where the thermoelement
is located. It retards the normal temperature rise at the
beginning of the melting and partly makes up the loss by
accelerating it at the end, thus increasing the obliquity of the
curve just where such increase is most undesirable. This
effect increases somewhat less rapidly than the rate of heating
and than the square of the diameter. The difference of tem-
perature between center and surface remains nearly constant
for small crucibles, but diminishes during melting for large
diameters and rates.
3. Magnitude of the distortion.—Dhiopside, a well-crystalliz-
ing silicate, melting at 1392°, showed a time lag of 24-46 sec-
onds for a crucible of 1 radius before melting began. The
charge was in shape a short cylinder. The latent heat was
enough to raise the solid over 300°, but was so distributed
that the maximum value of the virtual specific heat was only
about fifty times the true specific heat.
If, now, this substance is heated in a crucible of 1° radius
with a constant heat supply, giving a temperature rise before
melting begins of 8° per minute, the melting will last (roughly)
thirty-five minutes. The time lag (surface to center) would
by formula (6) reach twenty minutes for a charge all at the
maximum specific heat, but in this case, as experiment shows,
will be not much over half that. Even so, however, the period
of accelerated heat supply to the center will last ten minutes,
so that the last third (or more) of its melting will be distorted.
This third covers an interval of 2 to 8°. The resulting uncer-
tainty in the melting point would be less than that, and, there-_
fore, not very serious, but with a crucible of 4% diameter the
uncertainty would be much increased.
If the crucible has 1° diameter (‘5™ radius), the maximum
lag by formula (6) is only five minutes, or one-seventh the
melting interval, and the whole accelerated interval is not over
half a degree. If this smaller crucible, however, contains a
substance of greater purity, say sodium chloride, melting
through a 1° interval, the virtual specific heat might reach 400
times the true, and the accelerated interval would again cover
a third or more of the melting.
The distorting effect produced on the melting curve by the
normal gradient through the charge is, then, practically
important only in large charges, and though serious in them,
can be rendered negligible by a reduction of dimensions which
is easily attainable in practice. The distortion is also rela-
tively greatest in the purest substances, where the total
obliquity is least detrimental.
466 W. P. White—Melting Point Determination.
For naphthaline, the time lag was about three times that for
diopside. For metals, the conductivity is so great that distor-
tion of the kind just considered is probably always negligible
in practice. |
4, The above seems to justify the following practical con-
clusions: (1) For determinations of single points, the essen-
tial thing is to reduce the interval of accelerated heat supply.
This calls for small crucibles or slow rates. And when they
are used, the difficulties arising from the regular temperature
gradient across the charge can be rendered negligible compared
to other sources of error. The requirements of a given case
depend on the accuracy desired and on the purity of the sub-
stance, and can be determined well enough for all practical
purposes from the length of the melting interval in conjunc-
tion with the approximation just given for the relation of time
lag to radius in different substances. (2) Hor determining the
form of the whole melting curve, the time lag must be kept
small, and this again calls for the narrow crucible but not the
slow rate, for a reason given in the following paper (p. 485).
(3) Whether rate or radius, or both, shall be diminished will
depend mainly upon the apparatus and conditions at the dis-
posal of the investigator. The whole time required to com-
plete the melting varies nearly as V, the rate of heating. The
distortion varies as R*V, but V varies as G/R, where G is the
external gradient, hence the distortion varies as GK. also.
And, therefore, for the same distortion by diminishing R, V
and G are both increased. . So if R is made, say, one-third, the
run may be finished in one-ninth the time, and the effect of
variation or uncertainty in the furnace temperature also
diminished three times, with little increase in distortion.
V. Lrregular variations in heat distribution.—The preced-
ing section has dealt with an ideal case. It assumes a charge in
which the heat travels uniformly toward an infinitesimal ther-
moelement situated exactly at the center.. Of course these
conditions are never completely realized.
Sources of irregularity may lie in the furnace, in the charge
itself, or in imperfect centering of the thermoelement. Aside
from these, there is nearly always a tendency for melting to start
at one end of the charge, either top or bottom. In any case, the.
difficulty comes mainly from the fact that the melted area
reaches some parts of the thermoelement before others, so that —
the temperature of the junction depends on different por-
tions of the charge, some of which are melted while others are
not. This converts the ideally sharp break (X, fig. 3) into a
oradual rise, of uncertain interpretation. To avoid this diffi-
culty, two thingsare necessary. The thermoelement itself should
conduct heat as little as possible, and the melting should
W. P. White—Melting Point Determination. 467
approach it from the side and not from the end. This calls
for a thermoelement of fine wire, and for a charge narrow but
not too short. Failure to center the thermoelement is evidently
a minor fault. A thermojunction inclosed in a porcelain tube is
from the present point of view undesirable, since its temper-
ature is dependent on a considerable portion of the charge. A
resistance thermometer is evidently still worse. In fact, the
difference in sharpness is very marked between melting points
measured with an inclosed and a bare thermoelement. Buta
bare element of platinum wire °6™™ in diameter, immersed 8™™
in a cylindrical charge of 9X14™™", has been found to give
(from 800° up ) points quite as sharp as can be obtained with
wire much smaller. Since finer wire than this and narrower
and higher charges can be easily used, there seems to be no
difficulty in avoiding the effect of irregular temperature dis-
tribution for substances in which a bare element is admissible.
A few experiments indicate that at lower temperatures charges
narrower 1n proportion to their height may perhaps be needed,
but at lower temperatures they can also easily be employed.
VI. Conduction of heat along the thermoelement.—The ther-
mal conductivity of most substances is much less than that of the
metal thermoelement, so that the junction often receives heat
along the wires. This causes a gradual additional rise of
temperature toward the end of melting, thus increasing
the obliquity, and it also tends to make the final break come
high. ‘The effect is little altered by change of rate, since this
acts in the same way upon the heat, whether coming through
the charge or down the wire. It increases with the diameter
of the charge, since this increases the time of melting for the
saine external gradient. It is diminished by thinness of the
thermoelement, and by depth of immersion in the charge.
The avoidance of this cause of obliquity, then, demands the
same conditions as for the preceding, namely narrow and high
charges and fine thermoelement wires. And the experience
just now cited to show that the one cause of obliquity can be
easily avoided is equally conclusive with respect to the other.
On the other hand, an enclosed element, immersed 3 in a cru-
cible of sodium chloride, gave a melting point 7° too high.
This error is much greater than that found with some other sub-
stances melting at higher temperatures,* but it shows that
melting point results obtained with inclosed thermoelements
must be interpreted with care. A sufficient estimate of the
error resulting from heat conduction down the thermoelement
can in general be easily reached by varying the depth of
*See, e. g., Isomorphism and Thermal Properties of the Feldspars, pp.
23-25 ; Diopside and its Relations to Calcium and Magnesium Metasilicates,
pp. 3-4, loc. cit.
468 W. P. White—Melting Powmt Determination.
immersion. This method applied to 2°5 gram silicate charges
indicates that there was no perceptible error of this sort with
the element immersed 6 to 8™™, thus confirming the results
obtained by varying the size of wire.
VI. The use of bure thermoelements—From the fore-
going it is clear that in several ways a very great advantage
results if the thermoelement can be inserted directly in the
charge. But an error may then be introduced, due to the
electrical conductivity of the charge itself, which can not be
altogether neglected. At high temperatures, practically every-
thing conducts electricity to some extent.
The slightly conducting charge acts like a battery of very
high resistance connected in shunt across the junction.* The
effect on the galvanometer reading = such a battery is easily
shown to be practically equal to ee 5? where EH, is an E. Moe.
T, the (very low) resistance of the shunted portion of the
thermoelement, S, the (very high) resistance of the shunt.
It follows, first, that the leakage error increases with the depth
of immersion of the thermoelement and the fineness of its
wires, and second, that by dipping into a charge portions of a
thermoelement far from the junction the effect can be mag-
nified, and so a very delicate test made for it. Indeed, for
this test there need’ be no junction at all; if there is one,
either it can be kept at room temperature, or its E.M.F. can
be measured by making it also the junction of two other wires
which do not dip in the charge. In these ways it has been
shown that the error due to this effect, under the conditions
of our work, is not over one or two-tenths of a degree, either in
sodium chloride near 801° or in diopside near 1400°. It
was also shown, in the case of sodium chloride melted in a
erucible over a Bunsen burner, that the E.M.F. is thermo-
electric and is directed (in this case) from the electrolyte to the
colder of the two wires. Hence the error increases .with the
temperature differences present in the charge. The convection
currents of a large charge frequently reveal their presence
through the slight unsteadiness of the galvanometer, and in one
case the leakage disturbance from melt conductivity was
increased a hundred-fold by bringing a charge too near the
furnace top.t
The conditions making for small leakage error are therefore :
Uniformity of external temperature, smallness of charge, and
thickness and shortness of the immersed portion of the thermo-
*The effect would of course be the same if it were connected across any
other portion of the circuit.
.¢ It is therefore clear that the results just quoted as to the very small error
from conductivity of the melt should be applied with great caution in
extreme cases.
W. P. White—Melting Point Determination. 469
element. These are in part antagonistic to those required: for
diminishing effects V and VI, but with apparatus of the
dimensions given above, page 467, all these errors are reduced
to one or two-tenths of a degree or less.
Minor CavseEs oF OBLIQUITY.
VIII. Contamination of the thermoelement.—lIf the furnace
is heated continuously and more or less regularly throughout
the melting interval, the temperature of the furnace end
relatively to the charge steadily rises, and if the thermoelement
is not homogeneous between these two, its reading will rise
also.*_ In the case of a badly contaminated element at 1400°,
this apparent increase of obliquity was found seldom to exceed
1°. It practically vanishes if a constant temperature differ-
ence is maintained between furnace and charge, as also of
course if the element isin good condition; hence, while not to
be overlooked, it should never constitute a serious difficulty.
IX. Differentiation in the charge.—The portions of an
impure charge which crystallize last may have more impurity
in them, hence there may be a tendency for that part of the
charge immediately around the thermoelement to melt ata
lower temperature than the outside. This would tend to
increase the obliquity of the observed curve. Thus far, we
have not been able with certainty to distinguish this effect.
from the other accompanying causes of obliquity.
X. Ladiation through the charge.—lf the charge which is
bemg melted is diathermanous, direct radiation from the
crucible wall to the thermoelement will heat the latter, causing
a temperature rise which is greatest at the beginning of the
melting and which depends upon the fluctuations of the furnace
temperature. This effect, also, has not yet been distinguished
with certainty.
PRESENT STANDING OF THE PROBLEM.
Fig. 4A shows the typical melting curve of a fairly limpid
silicate (diopside). That the obliquity in the lower part of this
and similar curves is due to the substance itself (and therefore
to impurity) can be easily shown as follows: The obliquity
always precedes the melting, wherever that may occur, hence
it is due to the melting in some way or other, and not to the
furnace; that is, it indicates a true heat absorption accom pany-
ing the melting. When the heat absorption begins, the
thermoelement in the charge reads about 30° lower, and a bare
element exposed directly to the furnace outside the charge
reads (usually) 25° lower than the final melting point. Hence
* Phys. Rev., xxvi, 535, 1908.
470 W. P. White—Melting Point Determination.
no part of the very small charge can then be at or near the
melting point itself. And therefore some heat absorption due
to melting must occur at least 20° below the melting point.
The obliquity is also, within the experimental error, such as
would be expected from the known impurity, and can be
increased in silicates, and produced in substances originally
pure, by the addition of impurity. :
ine, 2h
10
0
Degrees
Heat
Fie. 4. Actual melting curves. A, Diopside (melting point 1392°). B, NaCl
(melting point 801°). OC, NaeSO,. (melting point 885°) (see text pp. 469-471).
The slope of the curve at the top from W to X is inconsist-
ent with equations (1) to (4) and is not easily accounted for by
any other known impurity effect. An attempt was made to
determine its cause. Variations in rate of heating, in the
depth to which the thermoelement was immersed, and in the
size of the wire, did not materially alter this part of the curve,
thus showing that neither distortion (effect IV) nor conduction
down the thermoelement (VI) was responsible.
An easily crystallizmg substance was next tried. Sodium
chloride (freezing point 801°++1°)* gave the curve B in fig. 4,
which shows the same peculiarity. Variation of rate and of
* This is a new determination,
W. P. White—Melting Point Determination. 471
size of thermoelement wire did not affect it perceptibly. The
freezing point here lay below the melting point as determined
from the curve. Hence in this case, the slope of the upper
end of the curve is due to the temperature measurement
and causes the melting point to come a little high. - Presum-
ably the same thing is true of the silicates giving curves like
A of fig. 4. In fact, the results obtained by adding different
amounts of impurity to one of these silicates are much more
consistent with each other and with equation (1) if the melt-
ing points are taken a degree or so lower than indicated by
the curves.
Sodium sulphate} (melting point 885°-+-1°)* was then tried.
The resulting curve is © of fig. 4. The whole melting inter-
val was 1° in one charge, 3° in another, which probably
became slightly contaminated in handling. For a temperature
so high, this isa remarkably sharp curve. Taken with the pre-
ceding it indicates that the false rise at the end of the melting
may be avoided, and that a clue to its cause may be found in
the physical differences between sodium sulphate and sodium
chloride at their melting points. A further investigation of
the problem seems to require apparatus not now at hand.
Meanwhile, the systematic error for the melting point deter-
mination in a limpid silicate has been reduced to a degree or
so, and the accidental variation to half a degree, and this
accuracy is obtained with exceedingly simple and convenient
apparatus. The error in the true melting point of these
silicates due to impurity is (in our case) quite as great as (and
opposite to) the experimental error. An attempt to realize
greater accuracy, probably attainable only through more elab-
orate experimental arrangements, has not seemed necessary at
present.+
The addition of impurity to the sodium sulphate of fig. 4,
C, gave the typical oblique curve of fig. 3
* This is a new determination.
+ From J. T, Baker Chemical Company, who gave the following analysis:
Ca, ‘005 per cent; Mg, none; Fe, ‘0006 per cent; Cl, trace.
¢In the work on Diopside, ete. (this Journal, xxvii, 8, 1909), the melting
points of the eutectic in different mixtures of pseudowollastonite and diop-
side are not quite the same, as by theory they should be, but rise with the
percentage of eutectic present, varying about 6°. The variation, though far
within the limits of error of most previous determinations at this tempera-
ture, is consistently greater than the accidental variations of our results.
Two causes for it are indicated by the present article: (1) Where the per-
centage of eutectic is larger and the time of melting, therefore, longer, the
false rise at the end of the melting curve is greater. These results are there-
fore a little too high. (2) Where the amount of eutectic is small the total
impurity present bears to it a larger ratio, and there is thus a tendency for
the melting point lowering to be increased—these results are thus a little
too low. It is probable that both causes are operative.
472 W. P. White—Melting Point Determination.
Hiittner and Tammann* point out the connection between
impurity and the obliquity of the melting curve, here devel-
oped in equations (1) to (4), and suggest that the form of the
curve may be a convenient means of estimating non-isomor-
phous impurities. They give a numerical computation for the
last half of the melting interval (or the first half of the freez-
ing interval), but appear to have overlooked the result which
would be obtained by carrying their calculation farther down
the curve, for they have no other explanation of the large
obliquity usually found there than conduction of heat along
the (bare) thermoelement, which they assign as the principal
source of obliquity. Their view as to the practical cause of
such obliquity is thus decidedly opposed to that reached in the
present investigation.
Y
Summary.
1. Actual melting and freezing point curves are nearly
always oblique—that is, they show, not the constant tempera-
ture called for by elementary theory, but instead, an interval
Ghee which the temperature continuously rises or falls.
The prime cause of obliquity in melting curves is the
spines of the melting itself, due to impurity. The true
melting point is the high end of the oblique melting interval.
3. The melting hysteresis of some very viscous substances
(mostly compounds of boron and silicon) is also an occasional
(and then serious) cause of obliquity.
A number of causes of obliquity le in the experimental
determination of the behavior of the melting and freezing
substance.
4. The determination of a melting curve necessarily involves
two factors: temperature rise, and heat supply; the latter
depends on the temperature difference of furnace and melting
charge; if this varies, the curve is distorted in a way striking
but easy to correct. The most common and conspicuous
example is where the furnace temperature is allowed to rise or
fall continuously, while the substance, melting or freezing,
remains nearly stationary.
5. The freezing point, coming at the beginning (in time) of
the interval, where temperature distribution in the charge is
relatively unifor m, is easier to observe than the melting point,
but is inadmissible in substances where undercooling is
marked. |
6. The melting point, coming at the end (in time) of the
interval, is lable, where stirring is not practiced, to obliquities
resulting from uneven temperature distribution: First, due to
the inevitable temperature difference between inside and out-
*K. Hittner and G. Tammann, Uber die Schmelzpunkte und Umwand-
lungspunkte einiger Salze. Zeitschr. f. Inorgan. Chem., xliii, 218, 1900.
W. P. White—Melting Point Determination. 473
side of the charge, troublesome with large charges, negligible
with small. Second, due to various irregularities in heat flow,
less with narrow charges and small thermoelements, hardly
ever over a degree or two. Third, due to conduction of heat
down the thermoelement, also less with narrow charges and
small thermoelements, for which it is usually negligible; but
possibly amounting to several degrees with inclosed elements.
7. Electrical conductivity i in the melt produces an error in
the reading of bare thermoelements, thus far negligible in
small charges of salts.
8. Contaminated elements, besides reading false, read so as
to increase obliquity.
9. Differentiation and diathermancy of the charge probably
increase obliquity.
10. Meltings have been made above 800° agreeing with each
other to -05°. In most cases an experimental obliquity
remains of from ‘5° to 1°5° (at high temperatures) whose cause
is still to be definitely determined.
‘Geophysical Laboratory, Carnegie Institution of Washington,
Washington, D. C., July 15, 1909
474. White—WMelting Point Methods at High Temperatures.
Art. XLV.—WMelting Point Methods at High Temperatures ;
by WaAtorR > Warm.
In an earlier paper of this series*, it has been shown that
for melting-point determinations up to 1600° C. the platinum
thermoelement, when used with a potentiometer (and with
suitable precautions against the effects of contamination), is
accurate, convenient, and rapid; the resistance-thermometer
is inadequate in range, and ill adapted to the special con-
ditions encountered ; the direct reading pyrometer is seriously
lacking in sensitiveness and accuracy and has very little advan-
tage in convenience where portability is not essential. Further-
more, potentiometers and galvanometers now on the market
are sufficient for the needs of the work, though special instru-
ments can be devised which are both cheaper and more con-
venient. As low as 1000° most solid insulators show signs of
an electrolytic conduction which increases with the tempera-
ture, while at about 1800° the air itself becomes conducting
through ionization, but the disastrous effect which the rela-
tively high voltage of the furnace current then produces on
the delicate electrical temperature measurement can be com-
pletely avoided by protecting the measuring system with a
metallic equipotential shield.
The present paper continues the discussion of apparatus
and of the varying procedure necessary to determine melting
curves according as the main object is the accurate location of
heat absorptions, their quantitative measurement, or their mere
detection when obscure.
Part I. The Apparatus.
I. The furnace.—The furnaces used in this laboratory are
nearly always of the type described by Day and Allen five
years ago.t For melting-point determination it has proved so
satisfactory that further experience has suggested hardly any
changes except variations in dimensions to suit different classes
of work. Platinum wire of smaller size (1:°2™™) has been
found to answer, which cuts the cost nearly in half, but a
specially pure platinum is now used in order to prevent con-
tamination of the thermoelement by the iridium vapor which
comes from the commercial metal. The furnace consists (1)
of the coil, which is more effective the nearer it is to the
* Potentiometer Installation, especially for High Temperature and Thermo-
electric Work ; Phys. Rev., xxv, 334, 1907.
+ Temperature Measurements to 1600° C.; Phys. Rev., xix, 177, 1904.
White—Melting Point Methods at High Temperatures. 45
working chamber, and is therefore wound on the inside of a
cylindrical furnace tube;* (2) of the cylindrical tube which
supports the coil, which must be refractory, a fairly good
insulator of electricity at high temperatures, not apt to crack
from heat, and of a material which can conveniently be
plastered on and baked, in order to repair the defects which
inevitably develop in use at the higher temperatures. Good
thermal conductivity in this cylinder is not disadvantageous ;
indeed, it probably tends to prevent cracking from unequal
distribution of the temperature. The dense mixture of mag-
nesia and various other ingredients sold by the Harbison-
Walker Company under the name of magnesite, which was in
use five years ago, is still the best material we know for the
purpose. (8) The outer layers of the furnace are merely
heat-insulating material—a layer of an inch or more. of cal-
cined magnesia powder around the furnace tube and a very
porous fire-clay outside of this and at the ends. The great
porosity of the fire clay has several advantages; the clay is
less likely to crack, it insulates heat better, and can easily
be pierced with holes wherever desired for the insertion
of thermoelements or other apparatus. These furnaces can
be brought to red heat in less than 40 minutes by a cur-
rent of 25 amperes, but will bear 40 amperes at the start.
The working current at high temperatures is about 20
amperes (2000 watts). At 1600° a heating rate of 5°
per minute has been safely employed, 7° at 1500°, and 12°
or more at temperatures 100° lower. How much more than
this the furnace can stand we do not know, and the attempt to
find out would obviously prove rather expensive. The furnaces
are heated by storage batteries, which furnish a practically
constant voltage. The heating rate can easily be regulated so
as to vary but 2 or 3 per cent from minute to minute, or a
stationary temperature can be kept constant within a degree
for hours with comparatively little attention. The real limit,
however, to the effectiveness of the temperature control is the
difficulty of securing uniformity of temperature throughout
the working chamber.
The extreme softness of platinum at high temperatures and
the tendency of the solid insulating and supporting materials
to shrink and crack call for the greatest simplicity and strength
in the form of construction, and practically compel the ordinary
furnace to take the form of a vertical cylinder, heated only on
the sides. The ends are always much colder and therefore any
body within the central cavity inevitably suffers from an
unequal temperature distribution, which is of course also
*For the method of winding, see Arthur L. Day and J. K. Clement, this
Journal, (4), xxvi, 411, 1908.
476 White—WMelting Point Methods at High Temperatures.
somewhat dependent on the body itself. Even in a horizontal
direction, considerable differences of temperature oceur. For
instance, a difference of over 4° has been found between two
points side by side wzthin a small porcelain tube of only 8™™
internal diameter in a furnace held steady at 1000°. In this
extreme case the tube was near the furnace wall, so that one side
was shielded from the cooling effect of the ends. With the
same tube in the center of the furnace the difference would not
reach 1°, though horizontal differences of 2° or so, often vari-
able from day to day, can hardly be prevented with large cruci-
bles, even when symmetrically located. The vertical differences
of course are greater. The furnace just mentioned was of our
“oeneral utility” type, with working chamber 6™ wide and
14™ high. Ina furnace built specially for uniform tempera-
ture with a higher and narrower cavity (4°5 x 23™), fitted with
four horizontal partitions to shield off the cooling effect of the
ends, the temperature variation over a crucible 4™ high was
20° at 500°, falling to 6° at 1500°. (Temperature differences
inside the furnace usually decrease with increase of tempera-
ture above 500°.) A small porcelain tube (4%™ diameter x 10™
long) in the center of the furnace chamber can be used to
reduce irregular vertical and horizontal inequalities of tempera-
ture when the crucible is small enough to go inside it. The
uniformity of temperature about the crucible is then. sufficient
for most melting-point determinations. For some other kinds
of work, notably gas-thermometry, where greater uniformity is
needed, other types of furnace have been developed. Con-
siderable success has been obtained by the use of auxiliary
eoils* and with a combination of furnace and bath, but these
are outside the field of the present paper.
For melting-point determinations with substances lable to
be altered by oxygen, the air has been excluded by a glazed
porcelain tube running through the furnace from top to bot-
tom. With a tube 4™ in inside diameter and 5:0™™ thick, the
melting of nickel (about 1453°) has been readily and satisfac-
torily observed.t The temperature distribution inside such a
tube has not been studied. A platinum tube closed at one end
has been used at various times to exclude air and also a closed
porcelain cylinder.t The method of controlling the atmos-
phere about the charge by the use of an air-tight inclosure
inside the furnace has, after trial of both, proved more effec-
_* Day and Clement, loc. cit., p. 412. See also, for a further account, a
forthcoming paper in this Journal on the gas thermometer, by Arthur L. Day
and R. B. Sosman.
+ Further details of this method will also appear in the forthcoming paper
on the gas-thermometer.
¢ The Role of Water in Tremolite and Certain Other Minerals, E. T. Allen
and J. K. Clement, this Journal, xxvi, 103, 1908.
White—Melting Point Methods at High Temperatures. 477
tive and much more convenient than inclosing the whole fur-
nace in an air-tight bomb.
Il. The crucibles—Two types of crucible installation have
been used for inversion and melting-point determinations.
The first is a relatively large crucible (5° in diameter) hold-
ing about 100 gr.* in which is inserted a porcelain tube for the
reception of the thermoelement. (See fig. 2, previous paper,
p- 455.) The porcelain tube is protected from the action of
silicate melts by a platinum jacket. This passes
through a platinum cover which shields the
charge somewhat from the cooling effect of the
furnace top. In ease it is desired to stir or add
to the charge when hot, the cover may be omitted,
but it is much better to retain it even then and
to add a second tube, opening into the crucible
below through an appropriate hole in the cover.
To prevent the platinum jacket from dropping
off the porcelain tube when hot, notches are filed
in the sides of the tube into which the edges of
the jacket are bent. The jacket can afterward
be twisted off easily by the application of a little
force.
The second type of crucible (fig. 1) holds
charges of about 1°. It is a platinnm tubet
borne on a porcelain tube open at both ends, to
which it is fastened in the same manner as the
platinum jacket described above. The thermo-
element is passed down through and guided by
the porcelain tube and its bare end dips directly
in the charge. To insure proper centering of
the junction in the charge (1) two capillary insu-
lating tubes are used, one on each wire; these
so nearly fill the larger tube as to be properly
guided by it; (2) these tubes are bronght as close
to the junction as possible without danger of their
touching the charge, thus leaving only 10 to 12™™ of the wire’
unsupported ; (3) the two capillaries and the wires are firmly
fastened together at the top, since a slipping of one wire up
or down relatively to the other will bend the junction to one
side ; (4) the wires are pushed into the melted charge very
*29 gr. charges have also been used in the past, but do not afford sufficient
depth of immersion for an inclosed element.
+ For substances which can easily be removed by melting them out, the
tube and crucible are preferably in one piece. For silicates, whose removal
usually requires hard pounding, it is more economical of platinnm to make
the lower portion, which stands the wear, separate. When in use, it is held
in place by crimping its edges over the slightly flared end of the upper por-
tion (as illustrated in the figure).
Am. JOUR. Pyaar Series, VoL. XXVIII, No. 167.—Novemser, 1909.
2
Fre. 1.
478 White—Melting Point Methods at High Temperatures.
slowly in order that the liquid may have time to yield, and
not deform the metal, which has very little strength at high
temperatures.
Each of these types of crucible has its advantages. With
the larger, the thermoelements may be changed or compared
during an ’ observation, the melted charge may be prodded or
sowed with crystals, or a sample may be taken, before heating
of the very mass of crystals whose melting- “point is to be
observed. With the smaller: (1) Melting “points are much
sharper, as pointed ont in the preceding paper. (2) selection
more uniform and steady distribution of the external tem-
perature can be secured (by using shielding tubes around the
_erucible). (8) The expense for material, and especially for
platinum, is far less—an important point with silicates, whose
removal after cooling rapidly uses up crucibles. (4) The eruci-
ble and charge can be removed and replaced again without
cooling the furnace. (5) By quickly inserting the charge in
the furnace or raising or lowering it when there, it can be sud-
denly brought to almost any desired temperature of crystalli-
zation. In particular, by removing the melted charge and
chilling it to glass, crystallization at some other temperature
may then be secured with certainty.
In some early work on wollastonite* we considered our-
selves fortunate when once a large crucible, cooled in the fur- —
nace, happened to cool below the inversion temperature before
erystallizmg and thus to give a cake of solid wollastonite.
With the small crucibles this condition has since been repeated
at will and rapidly.
Bare thermoelements dipping. into crucibles of about 20 er.
capacity have also been used where the heat absorption was
small and difficult of detection. Otherwise, their advantages
will be sufficiently clear from the foregoing.
The special element described by Dr. Dayt+ has, as far as
its original purpose is concerned, been superseded by ‘the small
crucible with the bare element. :
* Ill. The control element.—Since the thermal behavior of
a charge depends both on the charge and on the heat supplied to
it, some knowledge of the source of heat is always necessary.
To obtain it in delicate determinations, a “neutral body” has
often been placed in the furnace with the charge, whose behavior
is designed to show the effect produced by the furnace alone in
the absence of the peculiarities presented by the charge. The
control element as used in this laboratory differs from this —
device in giving, not the effect of the furnace temperature on
a third body, but that temperature itself. The difference is
* Allen, White and Wright, this Journal (4), xxi, 89, 1996.
+ Day and Allen, loc. cit.
White—Melting Point Methods at High Temperatures. 479
mainly a question of lag, but is often of considerable practical
importance.
Where a single element is used the furnace is regulated
for some time before the melting begins till a rate is assured
which will carry it through. This takes time, and also requires
judgment and experience, since the behavior of the furnace,
when left to itself, will depend not only on its individual
peculiarities just then, but on the conditions obtaining for
a long while previous. "With the control element, the observer
is in command of his apparatus from first to las st, and is
relieved from much uncertainty as to its condition. Again,
curves extending over long temperature ranges, with the single
element, must be done in sections. The furnace rate keeps
falling off, till it becomes necessary to stop, cool down a little,
and then start again. This not only is tedious, but is a gr ext
disadvantage with substances whose condition depends on their
previous history and is not wholly a function of their tempera-
ture at the instant. In one case we found a very important
effect which would either have greatly confused our interpreta-
tions or would have been missed altogether if our curve had
not been treated as a unit.
If meltings are carried on, as recommended in the preceding
paper, with a constant temperature difference between furnace
and charge, the control element is of course essential.
As actually used, the control element is merely inclosed in a
porcelain tube—completely in ordinary cases, projecting
(bare) beyond its open end where a specially close reading of
the furnace temperature is wanted. Below abont 1000° it can
be arranged to be read singly, and also differentially in opposi-
tion to the char ge element, so as to give directly the tem pera-
ture difference of furnace and char ge. At higher temperatures
this differential reading, on account of the tendency to leak-
age, requires special arrangements which are ordinarily some-
what inconvenient. The difference is then best obtained by
subtracting the separate readings, allowing, of course, for the
change of furnace temperature which usually occurs between
the taking of the two.
IV. Lhe thermoelements.—Thermoelements of platin-rhodium
are always used at high temperatures, on account of their
superior constancy. For insulators to use with these, the
Konighche Porzellan Manufactur makes tubes of so- called
Marquardtmasse. This material, when unglazed, bends slowly
if heated for some time in a horizontal position above 1500°,
but when used vertically, as in an electric furnace, it is sut-
ficiently retractory up to 1600°. It shows traces of conductiv-
ity as low as 1200°, but in our comparisons of thermoelements
at various temperatures no error due to this conductivity has
480 White—Melting Point Methods at High Temperatures.
ever been detected. The tubes used in our furnaces are of
two kinds, first an outer protectmg jacket 8™" internal, 10™™
external diameter, and closed below, separating the element
from the charge. "These tubes also make a convenient support
for small crucibles, as already described. When so used, they
can be many times inserted in and withdrawn from a hot
furnace without cracking, and their life is almost indefinite
when not subjected to this severe treatment. When glazed,
they are much less durable, cracking rather easily, and cannot
be used with tight- fitting platinum jackets, but have the —
important advantage of shielding the thermoelements from the
iridium vapor of the furnace. The other tube is an unglazed
open capillary of 2°” outside diameter, for insulating the wires
of the thermoclement from each other. Ordinarily, one wire
of the thermoelement is left bare. This is necessary in com-
paring elements, and more convenient in most other eases,
except with the small crucibles, as explained above (p. 477).
Recently, capillary tubes of. “quartz glass” have been put
on the market, which are cheaper than the porcelain and
impervious to most gases. Where a curved tube is needed,
they are indispensable, for they can be bent (in the oxyhydro-
gen flame) more easily than ordinary glass tubing. Above
about 950° they cease to be permanent, slowly devitrify (erys-
tallize), and become brittle, but can still be used where their
special advantages justify the trouble and expense of frequent
renewals when necessary.
To diminish the difficulties arising from contamination of
the thermoelements :* (1) Commercial platinum, with its high
content of iridium, must be banished from the furnace
altogether. (2) The elements used for the final measurements
are exposed to the high temperatures for the shortest time
possible. (8) They are also compared frequently with stand-
ards. (4) Great care is taken in standardizing to use the same
type of furnace and the same depth of immersion (almost to a
millimeter) as for the temperature measurement. (5) The
elements are cut off from time to time to remove the worst
contaminated portion. Of prime importance in this connection
is the factt that the reading of a thermoelement depends
mainly on the parts of it which lie in the steeper temperature
gradients. ‘The pains taken to preserve constant depth of ©
immersion are for the sake of keeping the same portions of
wire exposed to the same temperature gradient. In our fur-
naces a difference in depth of immersion of one centimeter
may alter the error of a contaminated thermoelement from 20
to 30 per cent. Where contamination has gone too far, it is
*Constancy of Thermoelements, W. P. White. Phys. Rev., xxiii, 463,
1906. Reprinted with important additions, Phys. Zeitschr., viii, 382, 1907.
+ Phys. Rev., xxvi, 535, 1908
White—Melting Point Methods at High Temperatures. 481
sufficient to cut off 2 or 3°", merely enough to bring fresh wire
down into the gradient region, which lies near the top of the
furnace. The time to do this is evidently when the contamina-
tion has become so great that the correction for it has more
than the allowable uncertainty. Practically, a lowering of
one degree in the reading is about the mit allowed in most
of the work of this laboratory.
The gas-thermometer scale is transferred to the thermoele-
ment by means of metal melting-points, which are therefore
the practical temperature standards in our work. <A thorough
treatment of this question will accompany the forthcoming
paper on the gas-thermometer. Here it is sufficient to say that
it is useless to calibrate contaminated elements directly by the
metal melting-point method, since the introduction of a large
crucible of metal into our furnaces seriously alters the tem-
perature gradients which previously prevailed. Extrapolation
is then particularly treacherous. But with wires of the homo-
geneity now attained in the Heraeus elements an element may
be relied upon to return to its original reading when properly
amputated. It is hardly necessary to say that the average of
several calibrations is more to be relied upon than a single one,
and this means that in case an element has been calibrated
several times with concordant results, and is then cut off to
remove contamination, for the new element thus formed the
average of the preceding calibrations is more to be relied
upon than a single new one. The same is true of a calibration
established by comparison of one element with another whose
calibration is known to be good. The opportunity for error in
the comparison, if properly conducted, is less than that in a
curve from a single set of melting-points made with equal care.
The calibration of contaminated elements, which requires a
particular temperature gradient, can be performed either with
charges of silicates or other salts, which will go in almost any
furnace, or by direct comparison with standards. The stand-
ards can also be used to calibrate new and perfect elements.
Such comparisons are also far less laborious than melting-point
determinations.
For very high accuracy in direct comparison it is absolutely
necessary that the two junctions be at the same temperature.
This is secured at high temperatures, either by thrusting the
two elements, without electrical contact, side by side into one
of the 8"™™ porcelain tubes and maintaining a uniform hori-
zontal temperature distribution around this tube (by a bath of
silver, a block of iron, or simply by putting the tube carefully
in the center of the furnace and surrounding it with a ballast
tube 4™ in diameter); or the two elements are first inserted
and read, then removed, transposed and inserted again, so that
482. White—Melting Point Methods at High Temperatures.
each is on the side of the tube opposite to-that occupied
before; or the whole tube, with the elements in it, is turned
around.
To keep the standards constant, interecomparisons are usually
made at no higher temperature than 1000°. The variation
measured at this temperature, if not over a degree, gives a
sufficient indication of the value higher up.
Part Il. Particular Methods.
I. Semple melting points.—To obtain these, it 1s necessary, —
after the furnace, crucible, and thermoelement are properly
arranged, to read the temperature of the charge at successive
intervals (one minute is usually often enough, though not
always) for from 5 to 15 minutes during the critical upper por-
tion of the melting curve, and at the same time to insure a fairly
regular rate of change in the furnace temperature. ‘To do this
the experimenter must (1) read (and record) the element in the
charge; (2) read the furnace control element beside the charge ;
(3) keep his galvanometer in correct zero adjustment; and (4)
regulate the furnace if the thermoelement readings show a
need for it. For this purpose he may first determine the fur-
nace rate each minute by subtracting the control element read-
ing from that for the previous minute.* The difference will
in general diminish steadily if the furnace is left to itself. It
can be kept constant and greater accuracy secured (pp. 461,
479, and 485) by regularly cutting out resistance from the
circuit of the heating current.
If a constant flow of heat into the crucible is desired, there
is usually a little imperfection in the furnace regulation near
the beginning of melting, when the progress of the furnace
temperature must be strongly checked. When the final melt-
ing temperature is reached the furnace is nearly stationary
and the regulation therefore particularly easy and satisfactory.
It is desirable for several reasons to watch the charge rate
also by subtracting the successive readings from each other.
The two subtractions and the furnace regulation can easily be
accomplished within a minute with good galvanometer arrange-
ments, and still leave the experimenter with the extra time
necessary to insure against oversights in switch setting or
arithmetical work. It is a little better if the two readings
come close together, so that the observer’s spare time during
each minute also comes all together. Readings can easily be
made within 10 seconds of each other. ‘To this end, however,
it is highly desirable that all intervals smaller than 100 mv. be ~
* Unless a direct differential reading is provided for, as described on P. 479
and illustrated on P. 484.
a
White—Meliing Point Methods at High Temperatures. 453
read as galvanometer deflections.* At the end of a determina-
tion the adjustment of the potentiometer storage battery is
verified by means of the standard cell, and the effect of elec-
trolytic leakage, if any, in the furnace is tested by breaking, or
better, suddenly reversing, the heating current.
Table I gives a typical notebook page for a melting-point
determination. All but the italicized portions belong to the
original record, made during the observations. Here the
furnace was first regulated for constant rate by the control
element alone, and then when the temperature difference cor-
responding to that rate had been found, it alone was used for
the rest of the observations.
Il. Melting points of viscous substances——Ilf the melting
shows much hysteresis (preceding paper, page 456), the thermal
method fails entirely. This difficulty, however, contains its
own remedy, for the viscous substance can at any time be
removed from the furnace near the expected melting point and
chilledt+ so as to fix the exact stage of melting then reached.
The portions already melted solidify to glass which is perma-
nent at room temperature. (With extremely viscous sub-
stances, even the chilling is not necessary, as recrystallization
takes place very slowly at any temperature.) This gives a sort
‘of “successive approximation” method of determining the
melting point. It excels the old methods of watching the sub-
stances in the furnace for signs of melting, in two respects; (1)
it is better thermally, since the furnace can be larger and more
completely closed, hence temperatures are more easily kept |
both constant and uniform ; (2) it 1s better optically, since the
substance is examined at room temperature.
Il. Quasi-calorimetric determinations.—It has been pointed
out in the previous paper that a melting-point determina-
tion involves some knowledge of heat supply as well as of
temperature. It is thus essentially a calorimetric determina-
tion and may easily be so conducted as to bear a calorimetric
interpretation, of greater or less accuracy. This may be a
determination of the entire melting curve, discussed in the
previous paper, or simply of the latent heat of a single change
of state. Hiittner and Tammann{ have given examples of the
latter, using a falling temperature, i.e., freezing instead of
melting curves. They take the heat loss as simply propor-
tional to the time, and propose the method as a rapid but only
an approximate one. Plato§ finds, by using a somewhat differ-
ent procedure, that the heat loss may be taken proportional to
*Compare Potentiometer Installation, etc. , Phys. Rev., xxv, 339, 1907.
‘+A. L. Day and E. T. Allen, this Journal (4), xix, £20; 1905.
{ Zeitschr. f anorg. Chem., ‘xiii, 215, 1905.
$ Zeitschr. f. phys. Chem., ly, 721, 1906.
484. White—Melting Point Methods at High Temperatures.
TABLE I.—TyYPICAL ORIGINAL RECORD OF A MELTING PoINT DETERMINATION.
NazSO4 + Element Na2SO.+
June 17, 1/3¢NaCl. immersed June 17, 1/3%NaCl.
1909. Charce dx 46 2 a 1909. Continued.
ne aS ee
po Ee Se io
= o ia a Ss a oO = all s
5 Pesce ape aca gi) as 60 2 0 ee
A ar .: oT #e5 2 oT : a, Ss
S 5 AUS 5 5 ans
7329 8142 156
54 13
7383 155 1538
50 | 10
74383 201 | 165 158
57 8
7490 7281 225 173 155
58 (i 6
7548 7358 205 iy 154
52 68 re
7600 7426 189 186 156
50 61 5
7650 7487 179 191 157
dl 58 | 5
7701 545 174 196 155
hi 4
602 17u 200 155 ©
56 3
698 165 | 203 156
5d 4
713 160 207 1538
51 3
764 153 210 148
50 2
814 151 212 150
Aq 2
861 148 8214 156
AT 3
908 152 217 158
48 16
956 152 233 144
46 44
8002 152 277 121
Al 45
043 158 322 140
36 60
079 156 383 150
26 64
105 157 446 148
22
127 155
15 Cadmium Cell balance O K
Each line of readings corresponds to one minute. The furnace was regulated each minute
when necessary. Readings in microvolts: 1MV=0°'09°.
White—Melting Point Methods at High Temperatures. 485
the square of the time after freezing begins, and claims very
high aceuracy. This method also involves some approxima-
tions and restrictions which, while not incompatible with excel-
lent agreement of the results, seem rather unnecessary, since
they can readily be avoided simply by a direct measurement
of the furnace temperature. Such a measurement is very
easily made; it gives at once and without any uncertainty the
temperature difference on which the heat supply to the charge
depends, and leaves the observer a wider choice of methods in
controlling his furnace. Its results are also of easier inter-
pretation than with the “neutral body,” whose temperature,
though a function of that of the furnace, is related to it in a com-
plicated way. In fact, no one seems to have attempted to deter-
mine heat absorption quantitatively by aid of the neutral body.*
The use of a single control element, though an improvement,
gives little more than a first approximation. The heat supply
to the charge is equal to GKT where G is the external tempera-
ture gradient, that is, the temperature difference of charge and
furnace, K is a heat-flow factor (conventionally called a radia-
tion factor), and T is the time. K varies with the absolute
temperature and this variation can be determined if a body of
known specific heat at different temperatures is available, or it
may often be negligible. _K also varies greatly with G, but
this variation is hard to determine, since the large values of
G which may occur during a melting often can not be obtained
at any other time.t The remedy for this difficulty is to keep
G constant throughout; this has the further great advantage
of eliminating the effect of systematic errors in G, which can
hardly be avoided. This procedure, however, since it changes
the furnace rate, tends to aggravate another source of error,
the variation in temperature distribution in the furnace, as a
result of which the control-element reading bears a different
relation to the mean effective furnace temperature at different
times. Attempts to avoid, by special apparatus and procedure,
this source of error have shown it to be very serious at high
temperatures, but have not as yet indicated clearly the most
effective means of diminishing it. Another source of error
lies in the differences of temperature within the charge, and
especially the difference between the thermoelement, in the
center, and the outside surface, from which the loss of heat
* See footnote, p. 460, previous article.
+ All the sources of error here treated have been hitherto disregarded in
work at high temperatures, though the least of them may at times cause an
error of 5 per cent of the heat quantity measured.
{ Plato, though he does not appear to recognize this difficulty, does in
fact avoid it by making what corresponds to a determination of K during
the violent temperature drop which immediately follows the freezing. But
this method seems open to grave objections, in spite of its excellent results
in his case.
486 White—WMelting Point Methods at High Temperatures.
actually occurs. This error is diminished, as shown in the
preceding article,* by reducing the diameter of the charge.+
All these effects conspire to make “radiation” calorimetry
somewhat analogous to some of the rapid volumetric methods
of analytical chemistry. Under strictly constant conditions
results can be reproduced with great uniformity, but their
actual accuracy is dependent, first, on a calibration by some
absolute method, and then on the subsequent absence of varia-
tion in numerous details, the importance of some of which may
easily be overlooked. The absolute method thus far available
in calorimetry at high temperatures is the method of mixtures,
where the body under investigation is dropped from the
furnace into a calorimeter.t Where that can be used, the
radiation method will probably depend on rapidity or con-
venience for its usefulness, but hardly seems likely to furnish
the final, most accurate values.
With most silicates, however, the dropping method cannot
be used, since their inversions and changes of state will not
occur normally with a rapidly falling temperature, and often
not even with a very slow fall. This makes the radiation
method more necessary, but at the same time deprives it of
independent calibration in the very region where that is most
needed, i.e., at the high temperatures where most silicates
melt. The rapid increase of K and consequent tendency
toward smaller values of G with rising temperature greatly
increase the disturbing effect of small variations in tempera-
ture distribution. A calorimetric problem of some difficulty is
thus presented, whose consideration does not belong here. It
has only seemed desirable to call attention to the present
limitations, as well as the possibilities, of such quasi-calori-
metric determinations as can be made with simple melting-
point apparatus.
As an illustration of these: numerous determinations, with
2-5 eram charges, of the latent heat of various silicates melting
above 1300° agreed to 3 per cent, but the systematic error may
be 15 per cent, so that it has not seemed desirable to publish
the results.$
* Pages 462, 466. The difference between center and outside is not only
smaller, but relatively more constant (p. 464) in the small charge. Its effect
almost disappears where G is kept constant.
+ Still greater accuracy has been obtained by making the crucible wall
itself the junction, and then measuring the temperature difference differen-
tially. Results are then consistent at least to 0°56 microvolt, or about -03°,
above 1400°.
t Plato, loc. cit. Goodwin and Kalmus, Phys. Rev., xxviii, 1, 1909.
J. A. Harker, Phil. Mag., x, 480, 1905, 1906. W. P. White, this Journal,
xxvili, 334, 1909. A full set of references in this subject might be hard to
make, and does not seem needed here.
SIf, however, the order of magnitude is of interest, it may be taken as
106+ 15 calories for diopside, about 350 times (numerically) the specific heat
of the solid just before melting.
White—Melting Point Methods at High Temperatures. 487
When the latent heat is small, as in most inversions, the
variations in the values of G, in the furnace rate, etc., are also
small, and the radiation method is easily made fairly accurate.
Two determinations of the inversion heat of wollastonite, made
with the simple 2°5 gram charge, agreed to 0°3 calories, and a
very generous estimate of the possibilities of systematic error
does not allow more than 1°5 calories.*
The experimental arrangement for quasi-calorimetric deter-
minations usually does not differ in any respect from that for
simple melting points at constant values of G. The determi-
nation illustrated on p. 484 was, in fact, quasi-calorimetric. For
the greatest accuracy the equipotential leakage shield (p. 474)
should be as complete as possible, and should be on the inclos-
ing 4™ tube, instead of connected to the crucible itself.+
The heat supplied to the charge within any interval is deter-
mined simply by adding the values of G{ for that interval;
since each value of G corresponds to one minute, this gives at
once the value of TG. A correction for the observed varia-
tion in K may also be needed. The other steps in the eal-
culation do not seem to call for special description.
IV. Small thermal effects —Some thermal effects, espe-
cially inversions in the solid state, are so slight that their mere
detection is a problem in itself. Determinations of this
character, like the preceding, depend on accurate heat meas-
urement, though here the behavior of the charge is no longer
a complication. The difficulty is rather to secure, in the fur-
nace itself, conditions so uniform and reproducible that very
slight variations occurring within the charge may be recog-
nized at once. This requires, of course, chiefly precision in
temperature measurement and regulation. It is also promoted
by increasing the size of the charge, thus increasing the tem-
perature difference, furnace to crucible, and diminishing the
effect of small temperature irregularities.
The feeble intensity of these thermal effects is usually due
as much to the slowness of the heat absorption or evolution as
to its small magnitude. Hence a rapid furnace rate, which
concentrates the effect, greatly aids in its detection. The
wollastonite inversion, for example, with a rate of 10° per
minute, can be accomplished in about 10 minutes with an
uncertainty of less than 1°5 calories (2°5 gram charge). Under
like conditions two calories should therefore be capable of
detection.
* The result was 10°0 + 1°5 calories.
+ The more elaborate arrangements referred to in the footnotes to page 486
are not properly within the scope of this paper.
t{ Really, the values of the temperature difference between center of
charge and furnace, which is greater than G by the amount of the gradient
in the charge, but proportional to it.
488 White—WMelting Point Methods at High Temperatures.
It is in determinations of this sort that the neutral body is
particularly advantageous,
If the inversion takes place promptly at a constant tempera-
ture (as for instance, with the quartz inversion at 575°) its
detection is evidently much easier. For the best results a
temperature reading should come immediately after the inver-
sion occurs, and before its effect has been dissipated by tem-
perature exchange with the furnace. The interval between
readings should be as short as possible with a rate about fast
enough to supply all the latent heat in one interval. A. rather
small fraction of a calorie could probably be detected in this
way.
Allen: Wright, and Clement* confronted this problem of
detecting small energy changes in their study of the mversions
of MgSiO, and finding the Frankenheim method inadequate
they developed a new one, whose essential feature was the
production of a very rapid rise of temperature in the substance
under examination by dropping it into a previously heated
furnace. The method here described is still the Frankenheim
method but with some improvements due to accumulated
experience. It is now several times as sensitive as is necessary
to detect one of the MgSiO, inversions.
V. Residual meltings. —The eutectic melting produced in
diopside by 2 per cent of pseudowollastonite is easily measur-
able on the smooth curve which precedes the melting point.
At the end of melting, however, as the last portions of solid
core or crust disappear in liquid, the temperature distribution
and variation in the crucible is irregular, and a rapid temper-
ature rise occurs. Hence, in the common case of eutectic mix-
tures containing a very small excess of one component, its detec-
tion may be impossible on an ordinary melting-point curve.
The accurate location of the eutectic, however, requires the
detection of these small residues as the composition of the
melt is varied in the adjacent region. For this purpose two
like crucibles may be placed symmetrically within the inner
tube, containing either two mixtures of slightly different com-
position whose relative nearness to the eutectic we wish to
determine, or two substances one of which is supposed to con-
tain and the other known not to contain the small residual
whose melting is being investigated. The temperature of
these is slowly and carefully raised until the (previously
measured) main melting point is just passed, an operation
requiring a little patience, but presenting no particular diffi-—
culty. The furnace will then be stationary. The tempera-
tures are read, the heating current of the furnace is suddenly
increased and alternate readings of the two crucibles made every
15 seconds as long as necessary. After the suspected region has
been traversed, the furnace is brought to a (higher) constant
* This Journal, xxii, 415, 1906.
White—Melting Point Methods at High Temperatures. 489
temperature, and the operation is repeated as a control expert-
ment to see if there is anything in the situation of the crucibles
or the peculiarities of the thermoelements calculated to imitate
the thermal behavior produced by the presence of a residual
in one more than the other. An example of such-a deter-
mination is given in a previous paper.* The magnitude of the
result there obtained with a 2 per cent excess of MegSiO,
indicates that at least -25 per cent could probably be recognized.
Summary.
1. Platinum resistance furnaces of simple construction pro-
vide complete control of the temperature for melting-point
work up to 1600° C. Where uniformity of temperature through-
out the working-chamber is important special modifications
are necessary.
2. Small charges (2°5 grams) give very sharp melting points,
are economical of material, and permit of convenient manipula-
tion.
3. A number of advantages result from the use of a second
thermoelement, which is made to give directly the furnace
temperature about the charge. The measurement and regula-
tion of the heat supply from the furnace is a factor of great
importance in accurate melting-point determination.
4. Methods of treating and insulating thermoelements and
of avoiding the effects of contamination have been developed,
suited to varions conditions and kinds of work.
5. The melting points of very viscous substances, showing
hysteresis, can be determined easily and effectively by very
slow heating, and occasional examination outside the furnace.
6. The approximate determination of latent heats of fusion
directly from melting curves is possible by measurement of
the furnace temperature, but is encumbered by several hitherto |
undetermined sources of error. The attainment of an accuracy
greater than 10 per cent (about 10 calories in many silicates)
accordingly requires special apparatus and procedure. The
smaller latent heats of inversion can usually be determined to
one or two calories with no other apparatus than the two
thermoelements.
7. For determining faint or sluggish thermal effects, rapid
rates of heating and the utmost precision in furnace regulation
and temperature measurement are needed.
8. The accurate location of eutectics by thermal means
requires the detection of small residues of the component in
excess. This can be accomplished by a special method in-
volving the use of a neutral body.
Geophysical Laboratory, Carnegie Institution of Washington.
Washington, D. C., July, 1909.
* Diopside and its Relations to Calcium and Magnesium Metasilicates, this
Journal (4), xxvii, 11, 1909. :
490 A. Agassiz—Kchinonéus Van Phels.
Arr. XLVI.—On the Existence of Teeth and of a Lantern
in the Genus Echinonéus Van Phels; by ALEXANDER
Agassiz. (With Plate IT.)
Waite making some preparations of the teeth of Echino-
néus for a report I am preparing on the specimens of the —
genus collected by the “ Albatross” in the tropical Pacific,
Mr. Magnus Westergren made the interesting discovery of the
presence of teeth and of a fully developed lantern (Plate II,
figs. 1, 38) in young specimens of the West Indian species of the
genus £7. semilunaris Lam. These young specimens (Plate II,
figs. 1, 2), measuring only 3-70" and 4:25™" in length, were
collected at. Port San Antonio, Jamaica, by Professor Hubert
L. Clark. This is perhaps one of the most interesting recent
discoveries in the domain of echinology, considering the rela-
tionship hitherto recognized of Echinonéus to the Atelosto--
mata. The presence of teeth would transfer them to the
vicinity of such types of the exocycla Gnathostomata as Holec-
typus, Discoidea, Pygaster (Echinoconide) and more remotely
to the Conoclypide.
The demonstration of this interesting relationship would be
interesting in itself, but its great importance les in the fact of
the disappearance of the masticatory apparatus at a very early
age. Young specimens of Echinonéus measuring 5°1™™ in
length, and but slightly larger than those in which teeth were
observed, have no teeth or lantern (Plate if, fig. 10) and noth-
ing is left of them but the presence of small auricles (Plate I,
fig. 4), so that in the older and adult stages of Echinonéus its
relationship to the Spatangoids is in no way modified.
The figures given on Plate [1 are sufficient to illustrate the
“novel points in the structure of Echinonéus. A more detailed
description will be given in a subsequent report on the genus.
Fig. 1,a profile figure of a young Echinonéus measuring 4°25™™
in length, shows the position of the lantern with its compass
and teeth as well as the course of the cesophagus and of the
wide folds of the alimentary canal (2’ and 2”) terminating in
the intestine leading to the anal system ; 2@ is a peculiar bag-
shape apparatus attached to the upper fold of the alimentary
canal, which is held in place by a line of mesenteries attached
toOvthe test,
Fig. 2, a transverse section of the test of a young specimen
of about the size of fig. 1, 3°70™™ in length, shows the actinal |
floor of the test from above, with the anal system (am) and the
lantern in place, as well as the pyramid (py), the compass, ¢,
and the pentagonal muscular band of the upper part of the
lantern (pm). 3
A. Agassiz—Kchinonéus Van Phels. 491
Fig. 10 is a profile view of a young specimen 5°16" in
length, in which the jaws, lantern and pyramid have disap-
peared ; the letterimg of the parts is as in fig. 1.
Fig. 3 shows the lantern more in detail; it is 1:3" in diam-
eter; oes is the opening of the cesophagus leading into the
lantern; pm, the horizontal muscular band of the lantern ;
ce, the compass; py, the pyramid; a, a, a, a, the small auricles ;
mc, the muscular band of the compass ; /, the labium.
Fig. 4 shows the position and shape of the auricles, a, of a
specimen 4°10™™ in length.
Fig. 5 shows the pyramid with the tooth (¢) seen from the
grooved side, while fig. 6 is the same showing the tooth from
the keeled side. The pyramids are solid without foramina. The
shape of the compass is shown in figs. 8 and 9, the profile and
dorsal views of the same.
The appearance of the young Echinonéus after the disap-
pearance of the lantern is shown in a profile view of the same,
fic. 10. How this disappearance takes place I am unable to
state, the material at my command showing no intermediate
stage between that of fig. 1 and of fig. 10. It is possible that
the lantern disappears by resorption; the whole of the calea-
reous deposits in the masticatory apparatus is most loose and
delicate. Its resorption would be in harmony with the resorp-
tion of many parts in the test and spines of other Echini.
It is interesting to note that this dentate stage of Kchino-
néus should connect the embryonic Spatangoids with the early
stages of Clypeastroids and of the Echinoconidee, while the
toothed Pygastroides of Lovén connects it with some of the
Echinoconide ; both Echinonéus and Pygastroides are West
Indian genera.
The presence or absence of auricles, teeth and pyramids
forms the basis of Zittel’s classification of the irregular Echini
into Gnathostomata and Atelostomata. The position of the
anal system on the actinal surface close to the actinostome is a
very modern feature: its gradual passage from an anal system
enclosed within the calycinal system as in Pygaster, where it is
outside of the abactinal system, can be traced towards the -
ambitus to the ambitus and finally to an actinal position.
In some of the Holectypide the jaws are greatly reduced in
size and solidity and their importance much lessened, and in
others the jaws have entirely disappeared, the perignathic
girdle having become rudimentary. In the Echinometrade
the auricular girdle is most highly developed. In the Holec-
typidee we find primitive irregular Echini as well as types
which have persisted to the present day. In the Discoidea and
Galerites the ambulacral processes and teeth are absent ; in the
auricular girdle the processes become low. In the Clypeas-
troids there are neither braces nor compass, the jaws move
492 A. Agassiz—Kchinonéus Van Phels.
horizontally, and finally in the Atelostomata the girdle and
jaws are completely absent. We may imagine the process of
resorption of the lantern of Echinonéus to have gone through
some such succession.
\
EXPLANATION OF PLATE IL.
a, auricle ; an, anal system ; c, compass.
7’, actinal loop of the alimentary canal.
i", abactinal loop of the alimentary canal.
ia, abactinal intestinal appendage.
labium.
m, madreporic tube.
mc, muscular band leading to compass.
mo, actinostome.
pm, pentagonal muscular band of summit of lantern.
py, pyramid.
t, tooth.
1. Profile longitudinal section of young Echinonéus measuring 4°25™™ in
length. .
2. Transverse section of young, 3°70™™ in length and 2°50™™ in width,
showing theactinal floor, the position of the lantern, and of the actinostome
seen from the abactinal side.
3. Lantern of Echinonéus magnified (1°30™™ in diam.) same as fig. 2.
4. Actinal part of ambulacral system seen from the interior of young
4:19™™ in length to show the auricles.
5. Pyramid and tooth seen from the exterior, length 0°85™™.
6. Pyramid and tooth seen from the interior, length 0°85™™.
7. Tooth seen in profile, length 0°62™™.
8. Compass seen from above, length 0°62™™.
9. Compass seen in profile, length 0°62™™.
10. Profile of young specimen measuring 5°16™™ in length ; the lantern and
auricles have disappeared.
Plate ll.
1909.
Vol. XXVIII,
Am. Jour. Sci.,
B. Meisel lith.
THE GENUS EGHINONEUS.
i it fiGhy »
| | NN OB pt
i t
ih He | ‘
‘ty TU
iby
i
i
ah
a
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Ny
1)
iN
Ba
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euitneis ae
NUON Caney
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Sait,
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Mi)
ie \
Chemistry and Physics. 493
SCIENTIFIC INTELLIGENCE.
I. CHEMISTRY AND PHYSICS.
1. The Separation of Titanium, Niobium and Tantalum.—
The quantitative separation of these three acid-forming elements
has been regarded as one of the most difficult problems of analy-
tical chemistry. Lupwieg Weiss and Max LanpEcKER of the
University of Munich have now made an elaborate study of the
matter, and they appear to have made a great advance in the
solution of this problem by the use of unexpectedly simple opera-
tions. An outline of their method for the analysis of columbite
and tantalite is as follows: ‘The usual fusion is made with acid
potassium sulphate, the resulting mass, after cooling, is extracted
with hot water containing sulphuric acid, and to the boiling solu-
tion sulphurous acid is added in moderate amount (20 or 30°)
until the precipitate loses its milky appearance and becomes
flocculent. After boiling for 20 or 30 minutes the precipitate,
which contains the tin and the rare acids, is filtered and washed
with a hot solution of sulphuric and sulphurous acids. It is
advisable to pass hydrogen sulphide through the filtrate and to
collect any tin that may have remained in solution. This filtrate
is then to be analyzed for the metals by the usual methods. ‘The
precipitate of acids is now treated thoroughly, as usual, with hot,
yellow ammonium sulphide for the extraction of tin. The residue
isignited and fused ina platinum crucible with sodium carbonate
and with the addition, shortly before the end of the fusion over
the blast lamp, of a little sodium nitrate in such a way (igniting
only for 8 or 10 seconds) that some of the latter remains unde-
composed. The amount of sodium carbonate should be only about
double that of the mixed acids, and the sodium nitrate should be
used sparingly. The mass is then extracted with boiling water
for some time in order to dissolve all the tantalate, the insoluble
titanium residue is filtered off, and a few drops of the filtrate are
tested with hydrogen peroxide for titanium. If this is present, as
is the case only when more than from 3to 5 per cent of titaniam
is present, hydrogen sulphide gas is passed into the cold liquid,
producing a grayish-white precipitate containing all the titanic
acid present here, and thus separating it from niobium and
tantalum. ‘This precipitate is washed with sodium sulphide. If
titanium is not present, carbon dioxide is led into the liquid in
order to precipitate tantalum and separate it from niobium,
but when hydrogen sulphide has been used it is necessary to
destroy the sodium sulphide with sulphuric acid, to precipitate
the acids with ammonia, and to make another fusion with sodium
carbonate and nitrate in order to obtain a solution suitable for
the precipitation of tantalic acid. This operation is performed
by passing the carbon dioxide for a long time in the cold. The
Am. Jour. Sci.—FourtuH Series, VoL. XXVIII, No. 167.—Novemper, 1909.
33
494 Scientific Intelligence.
precipitate begins to appear after 50 minutes. Then after passing
the gas for half an hour longer, when the precipitation is usually
finished, the liquid is boiled for a short time, and the precipitate
1s allowed to settle over night before filtering. The authors have
obtained very satisfactory results with these separations, but
much seems to depend upon the proper conditions in making the
fusion with sodium carbonate and nitrate. The original article
should be consulted in regard to further details..—Zeitschr.
anorgun. Chem., \xiv, 65. Haieawe
2. Hlectrical Discharges from Radium EHmanation.—In con-
nection with work on the collection of the emanation from about
0:2 g. of radium, DEBIERNE has observed spontaneous electric dis-
charges visible in daylight, in the little tubes containing the
emanation at atmospheric pressure. The sparks are often as
frequent as once a minute, and are sometimes several millimeters
in length. ‘They are usually produced in the interior of the glass
of the capillary tube, which is then furrowed with little cracks
resulting from their passage. The sparks often start from a very
brilliant point on the surface of the tube in contrast with the
emanation. Sometimes the electric discharge is produced across
the emanation itself, which is rather brightly illuminated. These
discharges are only produced with certain kinds of glass. A glass
which showed them most often was one containing lead, which
became violet under the action of the emanation, but glass con-
taining a large proportion of lead did not show the phenomenon.
The discharges may be attributed to the accumulation in the glass
of the electric charges of the a and 8 rays when the glass is a
sufficiently good insulator.— Comptes Rendus, exlviii, 1264.
me Wes
3. Outlines of Chemistry, by Louis KAHLENBERG 3 8V0, pp. XIX,
548. New York, 1909 (The Macmillan Company).—This is a
text-book designed for the use of college students. Itis intended
to represent one year’s work in connection with experimental
lectures and laboratory exercises, but no directions for experi-
ments are included in it. It is a rather large book containing a
comparatively large amount of descriptive matter. The theoreti-
cal discussions are distributed through the book in connection with
the appropriate facts. Quite a little attention is paid to historical
matters, and the most important technical applications have been
emphasized. . In general the work seems to be an excellent one,
and sufficiently different from the large number of books of
nearly the same scope to be well worthy of existence. Some
fault may be found with certain statements in regard to iron
and steel, but metallurgical weakness is characteristic of nearly
all of our text-books of general chemistry. The author’s attitude
towards the ion theory of Arrhenius is a surprising one for the
present day, for he rejects the theory as untenable, although he
gives a fairly extensive discussion of it. Perhaps this attitude
towards the ionic hypothesis may be considered preferable to its
too enthusiastic use in a text-book of this kind. H. L. W.
Chemistry and Phystes. 495
4. The Fundamental Principles of Chemistry, by Wi1LHELM
Ostwatp: Auvthorized Translation by Harry W. Mors: ; 8vo,
pp. xii, 349. New York, 1909 (Longmans, Green & Company).—
‘‘An introduction to all text-books of chemistry” is the sub-title
given to this book by its distinguished author. This does not
mean, however, that it is suitable for the use of beginners who
have no knowledge of the science. It is an essentially non-
mathematical discussion of chemical principles from physical and
philosophical standpoints, which will be of interest to more
advanced. students and teachers. The well-known attitude of the
author in discarding the atomic and molecular theories gives a
somewhat peculiar aspect to his theoretical considerations. He
uses “combining weight” in the place of atomic weight, and his
“molar weight” in the place of molecular weight appears to be a
mere makeshift. From this point of view his treatment of such
topics: as valence and ions is curious, to say the least. The
translation appears to be exceedingly well done. H. L. W.
5. Hlementary Modern Chemistry, by WiLHELM OstwaLp and
Harry W. Morse; 12mo, pp. 291. Boston, 1909 (Ginn &
Company). This small text-book is the result of the collaboration
* of the distinguished German chemist and an instructor in physics
in Harvard University. It gives an interesting series of physical
and chemical experiments, a moderate amount of descriptive
matter, and a good proportion of theory. Owing to Ostwald’s
peculiar views, the atomic weights connected with the list of the
elements are called “combining weights.” It may be observed
that this term does not apply as yet to argon, helium, etc. It is
also to be noticed that Avogadro and his theory do not appear to
be mentioned in the book. The illustrations are good, including
full-page portraits of Priestley, Ramsay, Dalton, Faraday, Ber-
thollet, Bunsen, Gibbs and Berzelius. Plaster-of-paris is charac-
terized as an anhydrous compound. The statement about wrought
iron “containing usually less than 1 per cent of carbon” is mis-
leading, and the view that suddenly cooled cast iron makes “white
iron or spiegel” is remarkable. These are small defects, and the
book on the whole has many excellent features. H. L. W.
6. On the Resistance due to Obliquely Moving Waves and tts
dependence upon the particular form of the forepart of a ship.—
Lorp Ray eicu refers to tlie train of waves which leave the bow
of ashijf These waves have been studied by the Froudes and
an analysis of them is given in Lamb’s Hydrodynamics (3d ed.
p- 414). More attention has been directed to the directly advanc-
ing waves, those whose crests are perpendicular to the ship’s
motion, than to the effect of the oblique part of the wave system.
Lord Rayleigh has made experiments upon a new form of bow
and stern which might neutralize the holding-back effect of the
additional pressure due to the crests of the train of waves, and
he suggests that larger experiments should be made, with what
may be called an undulating figure of bow and stern, instead of
the present convexity of these portions of a ship.— Phil. Mag.,
Sept. 1909, pp. 414-416. J.T.
496 Scientific Intelligence.
7. Excitement of Positive Rays by Ultra-violet Light.—The
origin of positive rays is sti]l undecided. Riecke and Ewers
attribute them to positively charged metal ions shot off from
the cathode metal. Gehrcke believes that they are due to the
light electric effect of the electric discharge on particles shot
out from the cathode. This higher electric effect results in a
redistribution of electrons, and the formation of positively
charged particles. W. Wien believes that a regeneration can
take place in a jar after an electric discharge has passed through
it and after the discharge has been submitted to the effect of a
magnetic field. H. DremBer has made: an investigation of the
production of positive rays by means of ultra-violet light. By
means of the Wehnelt electrodes and the rays of a quartz quick-
silver lamp, he was able to excite the rays by a small difference
in potential. The experiments were carried out over a large
range of pressures. The lowest pressure was obtained by means
of Dewar’s method of charcoal and hquid air, and extended from
0:000011™™ to 0°000008"™™" of mercury. ‘The curves obtained in
the extreme vacuum show that what may be termed jostling
ionization does not appear, and therefore the observed positive
particles arise from something shot off from the cathode. The
author describes two species of positive rays due to the light
electric effect.—Ann. der Physik, No. 11, 1909, pp. 187-165.
Saye
8. Electricity excited by the fall of Mercury through gases
upon the surfuces of metais.—This paper is of interest to meteor-
ologists and to those who hold to a belief in the theory of
contact electricity. The author, A. Becker, lets a fine stream of
pure mercury fall through a chamber, filled with certain gases,
upon surfaces of different metals, and measures the electric
potential. His facts are not in contravention to the arrangement
in series of the contact difference of potential of various metals.—
Ann. der Physik, No. 10, 1909, pp. 909-940. de 0
9. Viscosity of Gases.—Experiments have been conducted
in the Jefferson Physical Laboratory for several years by Dr.
J. L. Hoge on this subject. These experiments have led inci-
dentally to a comparison of the McLeod gauge and Maxwell’s
disc method. The latter method appears to be capable of great
accuracy, and Dr. Hogg has evaluated the viscosity of the quartz
suspending fiber. Gy. ZeEMPLEN adopts, to avoid the viscosity of
the fiber, a small deflection of a hollow sphere moving in a con-
centric sphere. He shows the applicability of the formula which
he deduced. It was found that the friction coefficient of dry atmos-
pheric air was independent of the rotation velocity (228 seconds
to 22 seconds), and that it is greater in moist air in certain limits
than in dry air.—Ann. der Physik, No. 10, 1909, pp. 869-908. .
Jans
Bie,
Geology. : 497
Il. Grotoey.
1. The Geology of the Queenstown Subdivision ; by JAMES
Park. New Zealand Geological Survey, Bull. No. 7 (new series).
Wellington, 1909.—This report of 112 pages, with geological
maps and numerous excellent photographs, published under
authority of Dr. J. M. Bell, Director of the Survey, treats one of
the most interesting districts of southern New Zealand, including
Lake Wakatipu, in the heart of the mountains between the plains
of the eastern slope and the fiords of the western coast. The
mountains, 6,000 to 8,000 feet in height, consist chiefly of Paleozoic
mica and other schists, compressed into closed overturned folds,
so as to give a general monoclinal dip of moderate or small angle
to the west. The chief longitudinal valleys are described as
established along overthrust shear-planes in the overturned
synclines, leaving the overturned anticlines to be less worn down
in the ridges ; but the text and maps do not present the facts in
sufficient detail to enable the reader to judge of the certainty of
- these conclusions. Fossiliferous Miocene sandstones are included
in one of the closed synclines; in one locality these beds may be
traced, in apparent conformity with the foliation of the schists,
from the bottom of a transverse valley at an altitude of 1,800 ft.,
_ obliquely up the mountain side to an altitude of 5,300 ft. “Such
profound involvement of a thin band of Miocene strata in a
highly altered Paleozoic formation seems highly incredible, but the
stratigraphical evidence could not be clearer, even if the Tertiary
sandstone were a contemporary bed of coal interbedded in the
schist” (p. 63). Pleistocene glaciation is described as having been
‘perhaps without a parallel outside the polar regions” (p. 25), the
polar regions of to-day being presumably referred to. All the
valley glaciers were united in a “great continental ice-sheet,” the
surface of which “formed a vast plateau, through which only the
tops of the highest peaks appeared.” The longest chapter in the
report is devoted to Economic Geology ; the gold-bearing lodes
being of most importance.
The discussion of certain topics is not so discriminating as
might be wished. For example, it is stated that “the lower arm
of Lake Wakatipu is doubtless to some extent a rift valley, as
may be judged by the dislocation of the schists on the two sides
of the lake” (p. 20); yet no evidence is presented to show that the
present depression of this arm of the lake is directly dependent
on the faulting, as ought to be the case in a rift valley; moreover
the structural sections clearly suggest that great erosion has taken
place since faulting. If the faulting once produced a depressed
trough, later erosion seems to have so profoundly modified this
initial form as to require another name than ‘rift-valley’ for the
present form. Again, the discussion of glacial erosion is inconclu-
sive, partly because the author seems to take Ramsay’s views on
this subject as adequate ; partly because the results reached are
498 Scientifie Intelligence.
presented more in terms of the author’s opinion than in terms of
critical facts of observation. “It does not necessarily follow that
the Wakatipu glacier . . . excavated the rock basin in which
the lake now lies. We know that the Wakatipu valley existed
prior to the glacial period, and there is good reason for the belief
that its origin has a close relationship to the powerful faults that
traverse each of the main arms of the lake. . . . It is possible,
or perhaps even probable, that a lake occupied a part of the floor
of the valley before the advent of the ice” (p. 40). On the
contrary, the ample breadth of the lake valley and the moderate
declivity of its side slopes show that the powerful faults have no
close relation to the valley ; and the abundant indications of
extensive normal erosion, following the period of mountain fold-_
ing and preceding the period of glaciation, are strongly against
the occurrence of a preglacial lake.
Furthermore, it is by no means demonstrated that ‘“a valley-
glacier with a wide hearing-surface relatively to its depth is
incapable of exerting a scooping action”; or that ‘ice can only
excavate its bed when the pressure of its mass exceeds the ulti-
mate crushing-strength of the bed rock.” Deductions from such
postulates as these are not to be trusted. There is unfortunately
no sufficient mention of the most critical elements of this problem,
namely the form of the lake-valley to-day, which is of much
greater value in determining the erosive work done by Pleistocene
glaciers than any deductive estimates of glacial erosion can be.
Whether glaciers erode their troughs slowly or rapidly, the
amount of erosion that they accomplished must be a function of
their duration; and as their duration is absolutely unknown, apart
from the work that they accomplished, it is better to look at the
consequences of their work recorded in their evacuated troughs,
than to infer their behavior on theoretical grounds, when the
attempt is made to determine what amount of sculpturing they
effected. W. M. D.
2. West Virginia Geological Survey; I. C. Waite, State
Geologist. Vol. IV. Zron Ores, Salt and Sandstones ; by G. P.
GrimsLeyY. Pp. xv, 603 with 24 plates, 16 figures. Morgantown,
1909.—This volume illustrates the fact that the geological survey
of a state can accomplish important results when the reports show
what results may be looked for in the future in undeveloped fields.
It is divided into three parts, discussing respectively the iron ores,
the salt, and the sandstones, including with the latter the glass sand
industry. The production of iron ore, which began in 1800 and
continued down until 1880, has now ceased entirely in consequence
of the introduction of cheaper ores, particularly from the Lake
Superior region. The detailed facts given in this Report show,
however, that there are extensive ore deposits, particularly suited —
for the manufacture of open hearth steel, which are available for
development in the future, when transportation conditions are
more favorable. What is regarded as a conservative estimate
gives 140 million tons as the amount probably available in five
Geology. 499
counties named. The salt industry of the state has also rapidly
declined in recent years, although at Malden and other points it
has survived in consequence of the valuable by-products of
bromium and calcium chloride. A larger demand in the future
is expected.
The treatment of the sandstones follows that of the limestones
described in Volume III. The Report contains much valuable
information as regards the different occurrences and the tests to
which the samples have been subjected. Here also it is noted
that a much greater extension of the industry in the state may
be looked for.
3. Geological Survey of New Jersey; Henry B. Ktmuet,
State Geologist. Annual Report for the year 1908. Pp. x1, 159,
with 21 plates, 6 figures. Trenton, 1909.—In addition to the
administrative report, the State Geologist contributes here some
further facts on the changes at Manasquan Inlet, and also
notes on the mineral industry of the state. The other two parts
of the volume are devoted to a general description of the zinc
deposits of Sussex County, by A. C. Spencer, and on the building
stones by J. Volney Lewis, the latter illustrated by excellent
colored plates. The report on the zine deposits gives some of the
results developed by work done in codperation with the U. S.
Geological Survey ; the facts are more fully presented in the
Franklin Furnace Folio noticed in vol. xxvii, p. 189.
4. Relations between local magnetic disturbances and the
genesis of Petroleum; by Gores F. Becker. U.S. Geol. Survey,
Bulletin 401. Washington, 1909.—The author has been led
from a consideration of the different theories for the origin of
the natural hydrocarbons, oil, gas, etc., to investigate the pos-
sible relations between the distribution of these hydrocarbons and
the variation of the compass needle. While some oils are doubt-
less of organic and others of inorganic origin, the fact that the
action of dry ammonium chloride on native iron results in a
copious evolution of hydrocarbons, suggests the derivation from
carbides of iron or other metals as an important source; it is well
known that such carbides exist both in artificial iron and in
various meteorites. By plotting the locations of petroleum
deposits in the country on a chart showing the isogonic lines for
1905, it is shown that the irregularities in the curves of equal
declination are strongly marked in the principal oil regions, and
the author regards these coincidences as too numerous to be
explained by accident. The relations thus brought out ‘‘are
compatible with the supposition that the great oil deposits are
generated from iron carbides, either by, or without, the agency
of water. Of these alternatives the latter is the more plausible.
What the map does prove is that petroleum is intimately associ-
ated with magnetic disturbances similar to those arising from the
neighborhood of minerals possessing sensible magnetic attraction,
1. e., iron, nickel, cobalt or magnetite. Henceforth no geological
theory of petroleum will be acceptable which does not explain
this association.”
500 Scientific Intelligence.
5. The Production of Coalin 1908 ; by Enwarp W. ParxkeEr.
—This advance chapter from the Mineral Resources of the
United States for 1908 has been recently issued. It shows that
the total amount of coal produced in the country aggregated
nearly 416 million short tons. This amount is less than the pro-
duction of 1907, in consequence of the business depression, by
some 65 million tons, but is greater than that of any year preced-
ing, even 1906. Of the total amount produced, one-fifth was
Pennsylvania anthracite and the remainder bituminous coal. The
details in regard to the different regions are given in this pam-
phlet. -
6. The Carnivora and Insectivora of the Bridger Basin,
Middle Hocene; by W. D. Matruew. Memoirs Amer. Mus.
Nat. Hist., Vol. IX, Part VI, pp. 291-559, with Pls. XLII-LI
and 118 figures in the text.—This is the most important memoir
on fossil mammals that has appeared in years and probably none
is better fitted than Dr. Matthew to carry out the task. It will
prove of the utmost value to all students and workers among the
Eocene Mammalia. The material upon which the monograph is
based is largely contained in the American Museum and is the
result of collections made during the years 1903-6. Comparison
has of course been made with the type material in the Yale,
Princeton, and National Museums.
The recent collections were made with such care that it is pos-
sible to discuss‘at length the five distinct stratigraphical and
faunal horizons into which the Bridger formations are divided,
with a table of their entire mammalian contents. The conditions
of deposition are next described, followed by a discussion of the
relationships and adaptations of the fauna as a whole, emphasiz-
ing particularly the degree of brain development which proved
so important a factor in the evolution of the various races. The
second section is given up toa study of the carnivorous types,
and, after a general discussion of the characteristics, adaptations
and relationships of the several families, each with its included
genera and species is defined in detail. Section III treats of the
Insectivora in the same manner. The fourth section includes a
discussion of the valne of the astragalus, upon which the author
lays great stress, in classification, a bibliography of 119 titles, and
a most copious index. B.S.
7. A Pliocene Fauna from Western Nebraska; by W. D.
MartHew and Harortp J. Coox. Bull. Amer. Mus. Nat. Hist.,
Vol. XXVI, Art. XXVIII, pp. 361-414, with 27 text-figures.—A
summary of the results of an expedition sent out by the American
Museum during the summer of 1908. The fauna, which is large
and varied, is intermediate between the Blanco and the typical
Upper Miocene and is equivalent to the Pikermi of Europe. It
differs from the Upper Miocene, to which it is most nearly allied,
(1) in the presence of more advanced species or mutations of the
several phyla, and (2) of certain Pleistocene or modern genera
not hitherto recorded from the Tertiary, (3) in the greater
Geology. 501
abundance and variety of three-toed horses, certain species. of
which show distinct approach to the Pleistocene Aquus and Hip-
pidion, and (4) in the abundance of gigantic camels of the genus
Pliauchenia. A new genus, two new sub-genera and a number
of new species are described. R. 8. L.
8. The Vertebrata of the Oligocene of the Cypress Hills, Sas-
katchewan ; by Lawrencx M. Lamps, F.G.S., F.R.S.C. Contri-
butions to Canadian Paleontology, Vol. III (quarto), Part IV,
pp- 1-64, with Pls. I-VIII and 13 text-figures.—In the introduc.
tion, Mr. Lambe gives a brief sketch of the discovery of the
Cypress Hills Tertiary beds, from which collections were made
for the Canadian Geological Survey in 1883, ’84, ’88, and ’89, and
finally by Lambe himself in 1904. The collections previous to
the last were described by Professor Cope, his final report appear-
"Ing in 1891 as part of the present volume.
The Cypress Hills deposits are correlated in a general sense
with the Oligocene Titanotherium beds, some of the upper
members being possibly synchronous w ith the Oreodon beds.
Whether or not the time- equivalents of the Protoceras levels are
here represented is problematical. In all over fifty species are
described, of which more than half are new. ‘They consist of
fishes, reptiles, and mammals, the latter including a marsupial,
ungulates, rodents, and carnivores. The plates are the result of
the author’s beautiful brush work. Restoke
9. Commisséo de estudos das Minas de Carvio de Pedra do
Brazil. Relatorio Final, Parte II, Mesosaurus braziliensis, nov.
sp. do Permiano do Brazil; by J. H. MacGrecor, 1908, pp.
302-335 and 5 plates.—This reptile was collected in the bitumi-
nous shales in the state of Paranda, southern Brazil, and is interest-
ing from two viewpoints : first in its adaptation to aquatic life,
being the first known reptile to forsake the land and return to the
habitat of its remote ancestors. The second feature of interest
is its reference to a genus hitherto known only from the Permian
of South Africa, and in fact indistinguishable from it, which is
further evidence for ancient land connection between the two
southern continents. R. Ss. L.
10. The Skull and Dentition of an extinct Cat closel y allied to
Felix atrox Leidy ; by Joan C. Merriam. Univ. of Cal. Pub.,
Bull. Dept. Geol., Vol. V, No. 20, pp. 291-304, with pl. ee
This huge cat is one of the remarkable assemblage of Quaternary
animals from the asphalt death trap on the Rancho la Brea, near
Los Angeles. The general form of the skull is remarkably sim-
ilar to that of the recent African lion and to the cave lion of the
European Quaternary. The immense size may be realized from
the measurements; among which the length is given as 395™",
or about 154 inches. aS) Les
ll. Zeratornis, a new Avian Genus from Rancho la Brea ;
by Love H. Mitter. Ibid., Vol. V, No. 21, pp. 305-317.—This
great raptorial bird from the asphalt deposits is much larger
than either the bald eagle or the California buzzard, and repre-
502 Scientific Intelligence.
sents one of a large group of birds of prey which evidently came
to feast upon the unfortunate animals entrapped in the asphalt.
Teratornis, while showing a preponderance of characters which
would tend to link it with the vultures, is considered as represent-
ing a distinct family, the Teratornithide. Ri Swe
12. Igneous Rocks. Vol. I, Composition, Texture and Classi-
fication; by Josera P. Ippines. Pp. 464, 8vo, 22 cuts and
figs. and 2 pls. New York, 1909 (Wiley & Sons).—It is promised
that a second volume will be devoted to the description and
occurrence of igneous rocks, this first one being confined to
what may be called the theoretical aspect of the subject. In
accordance with this the first chapter deals with the chemical
composition of igneous rocks, or magmas, and the various means
which have been used for diagrammatically representing chem-
ical relations among rock-groups, and of graphically picturing
rock analyses. This is followed by one in which the chemical
composition of the pyrogenetic minerals is treated. The third
chapter is especially timely and significant in that it presents in
clear, succinct form those principles of chemistry and physics
which are applicable to rock magmas and their solidification into
rocks. In this the latest views of physical chemistry which apply
to the subject are given, and many petrographers, students and
teachers alike, will find this one of the most useful and important
chapters in the volume. ‘The more igneous rocks and the pyroge-
netic minerals are studied the more evident it becomes that rock
magmas are mixed solutions and that the general laws obtained
from recent studies in physical chemistry are applicable to them,
as well as to the solutions usually studied in the laboratory,
modified by the conditions of high temperature. The author
here gives full credit to the illuminating work now being carried
. out in the Geophysical Laboratory of the Carnegie Institution.
This chapter is followed by one dealing with the chemical
reactions which take place in magmas; the chemical composition
of the important minerals and their formation and relation to
one another are considered. After this the separation of sub-
stances from solutions is discussed, and here the work of Vogt on
slags and of others in the field of physical chemistry are treated
in their relation to the problem in hand. Especially in its pre-
sentation of the réle of eutectics will this chapter be found of
value.
Following these matters of underlying and fundamental impor-
tance the actual crystallization and the texture of igneous rocks
are described. In respect to the latter feature the author uses and
amplifies the descriptive terms proposed not long since by himself
and several other American geologists in the Journal of Geology
(vol. xiv, p. 692, 1906).
The seventh chapter deals with the differentiation of igneous
rocks and under this heading a variety of subjects, such as petro-
graphic provinces, pegmatites, facies of rocks, hybrid rocks, order
of eruption and complementary rocks, is treated. This is suc-
Geology. 503
ceeded by one devoted to a description of the various modes in
which igneous rocks occur as geological bodies.
The second part of the work considers the nomenclature and
classification. After a short historical sketch the author presents
a qualitative mineralogical classification which is based in essence
on the quantitative classification in that the rocks are divided
first into five groups, as follows: 1, chiefly quartz; 2, quartz and
feldspar; 3, feldspar; 4, feldspar and feldspathoid; 5, chiefly
feldspathoid. These are subdivided according to the nature of
the feldspars into A, alkalic feldspars; B, calci-alkalic feldspars;
C, soda-calcic feldspars, and each of these has a subdivision
according to whether there is much or little ferromagnesian
mineral; a final group contains the rocks without feldspars.
Under these divisions the rocks, under the names ordinarily used,
are grouped, and while many names fall into certain compart-
ments it 1s interesting to observe that not many of the rock kinds
ordinarily recognized under the rather loose groupings now
employed, have to be split up. There is of course a further
division under texture and in the text explaining the table ceno-
typal and paleotypal habits are recognized.
The volume closes with a full statement of the quantitative
classification as previously presented by the author and others.
This volume in many respects, some ‘of which have been indi-
cated above, is the most important treatise on the theoretical side
of petrography which has yet appeared. It should be in the
hands of every teacher and advanced student of the subject.
In comparison with the work of Mr. Alfred Harker, also
noticed in this Journal, it is interesting to observe the different
standpoints of the two men. While the subject matter covered
is essentially the same in each work, Professor Iddings’s stand-
point is chiefly the physico- -chemical one, while Mr. Harker lays
weight on the geological aspect. Thus to draw a compari-
son from biology, one work is chiefly anatomical, the other faunal,
in its viewpoint. Thus in a measure the two works supplement
each other.
The typography, illustrations and general make-up of the
volume are excellent and a credit to the well-known firm of pub-
lisbers which issues it. DeVore
13. Natural History of Igneous Rocks ; by ALFRED HARKER,
8°, pp. 384; 2 pls., 112 diagrams. London, 1909 (The Macmillan
Co.).—The author states in his preface that the volume con-
sists in substance of the course of lectures delivered by him in
Cambridge University on petrology. He first considers igneous
action and igneous rocks from the purely geologic standpoint, and
emphasizes this aspect of the subject from the feeling that it has
not yet received the recognition it deserves as a part of historical
geology. In accordance with this we find the first chapter devoted
to igneous action, and after considering various regions the
author announces three distinct phases: (1) volcanic extrusions,
(2) plutonic intrusions, and (3) minor intrusions. When the
504 Scientific Intelligence.
normal cycle is complete, these follow in the order given.. The
second chapter is devoted to vulcanicity; if earth movements
are of two kinds, vertical movements, giving rise to plateau build-
ing, and horizontal ones, giving rise to folded mountain regions,
then there are two contrasted forms of volcanic eruptions, fissure
and central eruptions, the first connected with plateau-building,
the latter with mountain formation. Fissure eruptions are
normally quiet and non-explosive, while the central tyme gives
rise to active volcanoes.
The author then takes up the subject of intrusions and these
again he divides into two groups, as previously described for
extrusions. Laccoliths and sills are normal intrusions in plateau
districts, while stocks, batholiths, sheets and dikes are char-
acteristic for folded mountain regions. Curved lenticles of
igneous rock occurring in folded beds are termed p/acolites.
After this the subject of petrographical provinces is discussed
followed by the mutual relations of associated igneous rocks.
Under this Harker states that in volcanic extrusions the law
holds that succeeding eruptions are successively more diverse,
more acid or more basic, than the initial type, while in the major
intrusions the rule is that the most basic type is intruded first
and successive ones are more and more acid ; in the phase of
minor intrusions the reverse is true, the most acid types are the
older, the basic ones, such ds the lamprophyres, the younger.
Here also the question of increasing divergence arises to pro-
duce complexity and serial relationships. In following chapters
the writer discusses the chemical composition of magmas, the
physical properties of the rock-forming minerals, and the various
problems of crystallization which arise from considering the
solidification of magmas. ‘These subjects, which are of the
greatest interest to petrologists, occupy a considerable portion of
the volume and are treated in accordance with the most recent
views in physical chemistry. In this phase of the general sub-
ject the author mainly follows the ideas of Vogt. Successive
chapters on the structure of igneous rocks, on mineralizers and
pheumatolysis, and on magmatic differentiation, indicate also the
scope of the volume, which closes with an essay on classification.
The American quantitative classification the anthor views with
disfavor as being too artificial. He believes that the classifica-
tion should be a natural one based on the relationships of rocks;
he does not show how this is to be given practical form, but
leaves this for the future to determine and states certain princi-
ples which should govern attempts to formulate a classification.
The work as a whole is an interesting and important contri-
bution in the field of petrology; it contains new ideas and is
stimulating and should find a place in the working lbrary of —
every teacher and worker in this field of science. Ti Vee
14. Journeys through Korea ; by B. Koro. Journal Coll. Sci.
Imp. Univ. Tokyo, Japan, Vol. XXVI, Art. 2, 1909, pp. 1-207,
36 pls.—This work is the author’s second contribution to the
Miscellaneous Intelligence. 505
geology and physiography of Korea. The first was published
in the same journal in 1903 and entitled “ An Orographic Sketch
of Korea.” ‘This one presents the details of the geological obser-
vations made in three traverses across the southern part of the
peninsula. The general results are given in a summary with
geologic map and section of the route followed. Tliese show
that the general trend of the formation lines is somewhat west of
south, following the axis of the peninsula. The central axis is
composed of an immense area of gneiss flanked in general by
schists and sandstones and including masses of eruptive and
intrusive igneous rock, granites, porphyries, breccias, etc. The
outlying island of Quelpart is volcanic and composed of basalt.
A contact facies of a great mass of a rock determined as por-
phyrite is described as a porphyritic plagioclase greisen and named
masanite. The plates present a large number of fine views of the
country explored. ‘The whole forms a notable contribution to the
geology of eastern Asia, L. V. P.
Ill. Miscennanetovus Screntiric INTELLIGENCE.
1. Darwin and Modern Science: Hssays in Commemoration
of the Centenary of the Birth of Charles Darwin and of the
Fiftieth Anniversary of the Publication of the Origin of Species.
Hdited by A. C. S—ewarp. Pp. xvii, 595, with 5 plates. Cam-
bridge, 1909 (University Press).—Although it is “impossible to
express adequately in a single volume..... the influence of
Darwin’s contributions to knowledge on the subsequent progress
of scientific inquiry,” yet the papers here published together,
each by an expert and dealing with the present condition of. his
own special field of work, form a most remarkable series of
essays. Such of the papers as were originally written in German
and French have been rendered into simple English, and the
work of the editor has been done with such thoroughness that
the whole series forms a continuous and uniform account of the
present state of knowledge in a great variety of scientific fields.
The diversity of topics treated and the eminence of the con-
tributors will be seen from the following list of the twenty-nine
chapters: 1, Introductory letter to the editor from Sir Joseph
Dalton Hooker ; 2, Darwin’s predecessors, by J. Arthur Thom-
son; 3, The selection theory, by August Weismann ; 4, Varia-
tion, by Hugo de Vries; 5, Heredity and variation in modern
lights, by W. Bateson; 6, The minute structure of cells in
relation to heredity, by Eduard Strasburger ; 7, “The Descent of
Man,” by G. Schwalbe; 8, Charles Darwin as an anthropologist, by
Ernst Haeckel ; 9, Some primitive theories of the origin of man,
by J. G. Frazer; 10, The influence of Darwin on the study of
animal embryology, by A. Sedgwick; 11,12, The paleontological
record: I. Animals, by W. B. Scott, and II. Plants, by D. B.
506 Scientific Intelligence.
Scott ; 13, The influence of environment on the forms of plants,
by Georg Klebs; 14, Experimental study of the influence of
environment on animals, by Jacques Loeb; 15, The value of
colour in the struggle for life, by E. E. Poulton; 16, 17, Geograph-
ical distribution of plants, by Sir William Thiselton-Dyer, and of
animals, by Hans Gadow; 18, Darwin and Geology, by J. W.
Judd; 19, Darwin’s work on the movements of plants, by Fran-
cis Darwin; 20, The biology of flowers, by K. Goebel; 21,
Mental factors in evolution, by C. Lloyd Morgan; 22, The
influence of the conception of evolution on modern philosophy, by
H. Hoéffding; 23, Darwinism and sociology, by C. Bouglé; 24, 25,
The influence of Darwin upon religious thought, by Rev. P. N.
Waggett, and on the study of religions, by Jane Ellen Harrison ;
26, Evolution and science of language, by P. Giles; 27, Darwinism
and history, by J. B. Bury ; 28, The genesis of double stars, by
Sir George Darwin ; 29, The evolution of matter, by W. C. D.
W hetham. '
The volume thus produced by these distinguished authorities
affords an admirably thorough and comprehensive view of the
present condition of the broad field of science in which Darwin
was interested, and as it 1s written for the educated layman
rather than for the specialist, it commends itself to a wide circle
of readers. We B.C.
2. Les Zoocécidies des Plantes d’ Hurope et du Bassin de la
Mediterranée; par C. Hovarp; 2 vols., pp. 1247, with 2 plates
and 1365 text-figures. Paris, 1908 (Lib. sci. A. Hermann).—
This great work consists of a descriptive catalogue of all the
varieties of malformations, or galls, which are caused by animal
parasites on plants growing in Kurope and the Mediterranean
region. The list includes 6239 different kinds of galls. Most of
these are briefly described, and several hundred are illustrated.
These galls are produced by nearly 1200 species of insects and
268 species of arachnids. Such malformations are found ona
few species of Cryptogams, and on more than 2000 varieties of
flowering plants. Among the latter the oaks alone have more
than 800 different kinds of galls. The plants are arranged in
systematic order and their animal parasites indicated by name so
far as known. W. RB. ©.
3. Autogamie bei Protisten und thre Bedeutung fur das
Befruchtungsproblem ; von Dr. Max HarrMann, pp. 72, with
27 text-figures. Reprinted from the Archiv fiir Protistenkunde, _
Bd. xiv, Heft 2, 1909 (Jena).—An interesting and valuable
summary and discussion of the facts relating to endogamous
conjugation or self-fertilization in the unicellular animals and
plants. L. L. W.
4. Les Observations Méridiennes ; par F. Boquet. Tome I,
Instruments et Méthodes d’Observation, pp. 314. Tome I,
Corrections instrumentales et Equations personelles, pp. 342.
(Encyclopédie Scientifique, Octave Doin et Fils, Editeurs, Paris.)
—The comprehensive character and high grade of the Scientific
Miscellaneous Intelligence. 507
Encyclopedia, founded by Dr. Toulouse, to which these volumes
belong, has already been remarked in this Journal. The pub-
lishers now present two volumes in the library of Astronomy and
Celestial Physics, of which the titles are given above, both by
F. Boquet of the Observatory of Paris.
Opening it at random, we are attracted by the article on Self-
registering Micrometers, concluding with a description, clear as
the French language can make it, of the latest thing in Astro-
nomical Micrometers, the Micrometer Gautier, installed in 1903
at the Observatory of Paris, and since then in all leading observ-
atories of France.
An illuminated thread is fixed on the star and travels with it,
contact being noted for this thread on a point of reference.
Greater accuracy results than by the traditional method of noting
contact of the star with a fixed thread. W. B.
5. Ostwald’s Klassiker der Kxakten Wissenschaften. Leip-
zig, 1908 (W. Engelmann).—Recent additions to this important
series are the following:
No. 166. Entladung der Leidener Flasche ; intermittierende,
kontinuierliche, oszillatorische Entladung und dabei geltende
Gesetze. Abhandlungen von W. FEDDERSEN (1857-1866). Heraus-
gegeben von Tu. Des Coupres. Pp. 130, 3 plates and portrait.
No. 170. Abhandlung itiber die Glycole oder zweiatomige
Alkohole und tiber das Aethylenoxyd als Bindeglied zwischen
Organischer und Mineralchemie ; von ApotF Wurtz. Aus dem
Franzosischen tibersetzt und mit Anmerkungen versehen von M.
u. A. LapeNBuRG. Pp. 95, text figure.
6. Catalogue of the Lepidoptera Phalene in the British
Museum. Volume VIII. Catalogue of the Noctuide,; by Sir
GrorcE F. Hampson. Pp. xiv, 583, with 162 figures; also
plates cxxili-cxxxvi. London, 1909.—This eighth volume of the
British Museum Catalogue of Moths is devoted to the second
part of the Noctuid subfamily Acronyctine. It includes 104
genera with 702 species, while the seventh volume (see v. xxvii,
p. 492), which preceded, contained 96 genera with 843 species.
‘There remain 171 genera, which will be discussed in the final
part of the subfamily, soon to appear. The text is accompanied
by a volume of beautifully executed plates illustrating’ the spe-
cies described.
7. Les Prix Nobel en 1906. Stockholm, 1908 (P. A. Nor-
stedt & Sons).—This recently issued volume presents the facts
in regard to the distribution of the Nobel prizes of 1906. It.
gives portraits and biographical notices of the recipients, and
representations of the Nobel medals and diplomas. The prizes
in science were awarded to Joseph John Thomson and Santiago
ramon y Cajal in Physics, to Henri Moissan in Chemistry, and to
Camillo Golgi in Physiology and Medicine. The volume closes
with the lectures deliver. d at Stockholm, in December 1906, by
J. J. Thomson, C. Golgi and Santiago Ramon y Cajal.
508 Scientific Intelligence.
OBITUARY.
Dr. JoserH FREpERIcK WuirEaves, LL.D., F.G.S., F.R:S.
the distinguished paleontologist to the Geological Survey of
Canada, died at his home in Ottawa on August 8 last, in his
74th year., Born in Oxford, England, on the 26th of December,
1835, he was early attracted to the pursuit of Natural History in
his native city, and began by collecting the land and freshwater
shells of the neighborhood. Later most of his time was devoted
to collecting and studying the Jurassic fossils of the country
around Oxford. In 1861, Dr. Whiteaves arrived at Quebec,
Canada, and then proceeded to Montreal, where he became
acquainted with Elkanah Billings, paleontologist of the Canadian
Geological Survey. From 1865 to 1875, he was Curator of the
Museum of the Society of Natural History at Montreal, publish-
ing papers in the meanwhile on the land and freshwater mol-
lusea of Lower Canada, the Ordovician fossils of the Island of
Montreal, and the living marine invertebrates of the Gulf of St.
Lawrence. In 1875, he joined the Geological Survey of Canada
as associate paleontologist with Elkanah Billings, succeeding
in 1876 to the office of paleontologist, a position he held up to
the time of his death. In 1883 he received the additional
appointments of zoologist and assistant director. During these
thirty-four years.of service he published more than 100 papers on
Canadian paleontology and zoology.
Dr. Whiteaves was one of the original Fellows of the Royal
Society of Canada, and was an active Fellow of the American
Association for the Advancement of Science between 1882 and
1899, and Vice President of its section of Geology and Geography
in 1899. In 1900 he received the degree of LL.D. from MeGili
University, Montreal. His chief work has been in making known
the stratigraphy and paleontology of western Canada. 6.8.
Hueu Fretrcuer, geologist of the Canadian Government, died
of pneumonia, September 23d, at Lower Cove, Cumberland,
Nova Scotia. He was born at London, December 9, 1848, and
came to Canada in 1863. In 1872 he jounce the Geological Sur-
vey of that country, after taking the B.A. degree at Toronto the
previous year. During his thirty-seven years of active geological
service he did much to develop the mineral resources of Nova
Scotia, especially the coal deposits. His’ official reports are volu-
minous, carefully prepared and detailed. Ue stood high among
the mining men of Nova Scotia, and also among American geol-
ogists. He leaves a son and daughter. Cc. S.
Dr. Anton Dourn, the eminent zoologist who founded and as
director developed the Biological Station at Naples, died at
Munich on September 26 at the age of sixty-eight years.
VOL. XXVIII. DECEMBER, 19-2.
—
, Established by BENJ AMIN SILLIMAN in 1818.
THE
AMERICAN
| JOURNAL OF SCIENCE.
Eprror: EDWARD S. DANA.
ASSOCIATE EDITORS
Proressors GEORGE L. GOODALE, JOHN TROWBRIDGE,
W. G. FARLOW ann WM. M. DAVIS, or Camsringz,
Proressors ADDISON E. VERRILL, HORACE L. WELLS,
L. V. PIRSSON anp H. E. GREGORY, or New Haven,
Proressor GEORGE F. BARKER, or PHmaDELPHIA,
Proressor HENRY S. WILLIAMS, or ItHaca,
ProressorR JOSEPH S. AMES, or Battimore,
Mr. J. S. DILLER, or Wasurneron.
FOURTH SERIES
VOL. XX VUI—[W HOLE NUMBER, CLXXVIII.]
No. 168—DECEMBER, 1909.
NEW HAVEN, CONNECTICUT.
1909.
THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 123 TEMPLE STREET.
ee eee
Published monthly, Six dollars per year, in advance. $6.40 to countries in ‘the
Postal Union ; $6.25 to Canada. Remittances should be made either by money orders,
registered letters, or bank checks (preferably on New York banks). A
Announcement of New Arrivals,
Iceland Minerals.
I have just received after considerable delay a new lot of Iceland Zeolites
consisting of one hundred specimens. The species represented are Heuland-
ite, Stilbite, Epistilbite, Scolecite, Ptilolite and Quartz geodes in both
Museum and cabinet size specimens, which I have priced at far below former
values placed on these choice trap rock minerals. Their beauty, brillianey
and the quality of the crystals is finer than any former lot brought to this
country. | :
‘ Minerals from Franklin Furnace, N.J-
I have also been fortunate in obtaining a very old collection from a gentle-
man who specialized in Franklin Furnace minerals and which contains many
duplicates of finely crystallized specimens. For instance, several of the ex-
tremely rare crystallized Zincites as well as Franklinites, Rhodonites, Troost-
ites in very large crystals; also Gahnite, Tourmaline, Calamine, Garnet and
Spinel. An exceptional lot of choice Phlogopite in Calcite of the largest
size found.
Minerals from Colorado.
Recent additions to my large stock of the desirable Cripple Creek Tellur-
ides include specimens of the very best quality obtainable. such as Tellu-
rium, Sylvanite, Calaverite, Gold, etc. With these came Amethyst in parallel
erowth of exquisite quality and a crystallized Calciovolborthite and Carno-
tite from Telluride, Col.
Minerals from New Mexico.
A number of Vanadinites have been received from New Mexico, which
show crystals distributed over Barite matrix forming desirable specimens of
beautiful contrast. Also a number of fine native Silvers from the same
locality.
Desirable and timely gifts for Christmas of cut gems, gem crystals, antique
cameos, opal carvings, with semi-precious stones cut and polished and adapt-
able for mounting in pins, brooches, ete.
The large stock carried places me in the best position to cater to the many
requirements of my patrons for either minerals, rare or common gems, as
well as the highest quality of reconstructed Rubies, Sapphires, blue or white,
and the beautiful new pink Topaz.
I would be pleased to send on approval for inspection aud selection any-
thing that would interest my patrons,
Information as to special lists and prices of individual specimens cheer-
fully furnished.
A. H. PETEREIT, |
81—83 Fulton Street, New York City.
bash Ad
AMERICAN JOURNALOF SCIENCE.
[FOURTH SERIES.]
OO
Arr. XLVIL.—The Ordovician and Silurian Formations in
Alexander County, Illinois ;* by T. E. Savacs.
Location and Earlier Work.
Rocks of Ordovician and Silurian age are exposed in south-
west [linois only over a narrow belt, less than four miles in
maximum width, bordering the Mississippi river. The line of
outcrop of these strata extends along the west side of Alex-
ander county, and continues north about two miles into the
southwest corner of Union. .
For almost forty years practically no work was done on
these horizons in this portion of the state. In 1866, Worthent
described a bed of massive, light gray, semi- crystalline hme-
stone, outcropping near Thebes, as the lowest strata exposed
in this part of Illinois, and corr ectly referred it to the Trenton
(= Mohawkian) series. Concerning the Cincinnatjan strata in
this region he says :{
“They consist of about 100 feet in thickness of brown,
sandy shales and regularly bedded, brown sandstone (Thebes
sandstone and shale) which forms the lower portion of the
group; overlain by about forty feet of thin-bedded, com-
pact, fine-grained limestone—which breaks with smooth, con-
choidal fracture’ (Cape Girardeau limestone).
Under the name Clear Creek limestone§ he described a group
of siliceous limestones in this region which immediately suc-
ceed the Girardeau. These he interpreted as occupying the
same stratigraphic position as the Niagara dolomites in the
northern part of the state.
* Published by permission of the Director of the Illinois Geological Survey.
+ Worthen: Geol. Surv. IIl., vol. i; p. 148.
t Ibid., p. 139. S Tbid., p. 126.
Am. Jour. Sct.—FourtH Series, VoL. XXVIII, No. 168.—DrcremBer, 1909.
34
DLO wT nt: Savage—Ordovician and Silurian Formations.
In 1868 there was published a detailed report on the geology
of Union and Alexander counties,* based on the studies of
A. H. Worthen and Henry Englemann. In this work the
divisions of the Ordovician remain unchanged, but the term
“Clear Creek limestone” is restricted to only that part of the
siliceous limestones which is correlated with the Oriskany
series of the Devonian. ‘To the Silurian there is referred the
lower 250 feet of these deposits under the name Lower Hel-
derberg limestone.
In this report Worthen referred the so-called Lower Hel-
derberg limestone to a horizon higher than that of the Niagara
dolomites in northern Illinois. In 1870 he reverted to his
earlier views and correlated these limestones with the Niagara
dolomites farther north,t explaining the difference in the
specific character of the fossils in the respective deposits as
‘entirely due to the difference in the oceanic conditions under
which they were laid down and not to the different ages of the
sediments themselves.”
Since 1870 no careful study of the above mentioned beds
has been made until detailed work was taken up by the writer
during a part of the summers of 1907 and 1908. In the col-
lection of fossils the exposed ledges were worked by layers,
or arbitrarily divided into zones from six inches to a very few
feet in thickness. The fossils from each of these layers or
zones were kept: separate in order to determine the vertical
range and the relative abundance of the different species.
This detailed manner of work has revealed the presence of a
surprising number of unconformities, some of which would
not have been detected by any marked change in lithology, or
by a less careful method of study. In a preliminary statement
of the results of this work, a general section of the deposits
has been given.{ |
Conditions of Deposition.
The strata under consideration were laid down in an
arm of the sea which had connection southward with the
Mexican gulf region along a depression now occupied by
the lower course of the Mississippi river. Up this embay-
ment the sea pulsated backward and forward. Through the
southward connection the successive faunas reached the part
of the basin under consideration and spread towards the north,
east and west, to a greater or less distance, with increasing or
decreasing depth of the water. A short distance to the west of ©
* Worthen: Geol. Surv. Ill., vol. iii, p. 20 et seq.
+ Worthen: Proc. Am. Assoc. Adv. Sci., vol. xix, pp. 172-175
{ Savage, this Journal, vol. xxv, pp. 481-448, 1908 ; also, Tl. ‘State Geol.
Surv., Bull. No. 8, pp. 108-117, 1908.
T. E. Savage—Ordovician and Silurian Formations. 511
this area the embayment was bordered by the Ozarkian land
mass. On account of the proximity of the shore, the sea was
generally shallow, so that even minor movements were regis-
tered in the deposits. As a consequence of these conditions
there occur here a surprising number of breaks in sedimenta-
tion, recording a remarkable number of oscillations of level
during the Ordovician and Silurian periods; and during the
interval, generally represented by land conditions, between the
deposition of the uppermost Richmond beds and the basal
deposits of the Clinton.
Succession of Strata.
The relations of the various formations representing the
Ordovician and the Silurian Systems in this region are shown
in tabular form below:
2 Clinton Sexton Creek limestone, 16—70 feet
= E
ux. : d Edgewood limestone, 0-12°5 feet
eat Alexandrian ;
R , Girardeau limestone, 18-33 feet
Cincinnatian Orchard Creek shale, 17-22 feet
=I ia oor Te EA
"3 Thebes sandstone, 75 feet
>
= Mohawkian Fernvale limestone, 0-3°5 feet
= Kimmswick limestone, 70-82 feet
ORDOVICIAN SYSTEM—MoOHAWKIAN SERIES.
Kimmswick Limestone.
The name Kimmswick was applied by Ulrich* to a bed of
gray, thick-bedded, subcrystalline limestone exposed in the
vicinity of Kimmswick, in Jefferson county, Missouri. These
beds correspond in their lithology and fauna with those appear-
ing in the railroad cut and river bank a short distance south of
Thebes, which Worthen referred to the Trenton. The above
name is retained for these strata in southwest [linois which
contain the fossils eceptaculites owent, Dalmanella testudi-
naria rogata, Platystrophia biforata, Rafinesquina alternata,
Parastrophia hemiplicata, Strophomena trentonensis, Rhyn-
chotrema mequivalve, Zygospira recurvirostra, Bronteus
lunatus, Bumastus trentonensis, Lllenus americanus, Isotelus
cf. maximus, Platymetopus cucullus and Remopleurides
striatulus.
* Ulrich: Mo. Bur. of Geol. and Mines, vol. ii, 2d series, p. 111, 1904.
512 7. &. Savage—Ordovician and Silurian Formations.
The outcrop of this formation is limited to a few small
patches in the bank and bed of the river, in the vicinity of
Thebes. The Kimmswick beds differ in their lithology and
fauna from those of any horizon in the Mohawkian series in
the northern portion of the state, with some part of which
they were doubtless contemporaneous. A barrier of some
kind probably separated the two areas during the time of
deposition of the respective beds.
Correlation.—Out of thirty-five species of fossils listed from
the Mohawkian strata of Minnesota* which are also found in
the Kimmswick limestone of Illinois, nine appear below. the
Trenton, six of which persist into the lower Trenton beds;
twenty occur in the lower division of the Trenton (Clitam-
bonites bed), nine of which continue upward into the over-
lying division ; twenty-four species occur in the middle division
(Fusispira bed); while only a single one of these is found in
the upper division (Maclurea bed). From these facts the
Kimmswick limestone is thought to correspond, in time, with
some part of the middle division of the Trenton (Fusispira bed)
of the upper Mississippi valley.
The Post-Kimmswick Unconformity.
An erosion interval succeeding the deposition of the
Kimmswick limestone is shown in the fact that the thickness of
this limestone varies from place to place, and the upper portion
of the formation is not a constant horizon. Land conditions
are also indicated in the presence, at the top of the formation
at Cape Girardeau and other points, of solution channels filled
with red colored, residual clay. The time involved in this
erosion period was long. Some of the upper part of the
Mohawkian and all of the Utica and Lorraine deposits are
wanting.
CINCINNATIAN SERIES.
The rocks of the Cincinnatian series in Alexander county
are all embraced in the Richmond stage. They comprise three
distinct formations: 1, the Fernvale limestone at the base; 2,
the Thebes sandstone, and 3, the Orchard Crsek shale.
The Fernvale Limestone.
Overlying the Kimmswick strata is a thin bed of hard, gray.
limestone, bearing Rhynchotrema capax, Dinorthis subquad-
vata and other fossils characteristic of the lower portion of
the Richmond stage. Strata containing similar fossils have
* Geol. and Nat. Hist. Surv. of Minn., vol. iii, pts. 1 and 2.
T. E. Savage—Ordovician and Silurian Formations. 518
been described by Ulrich and Hayes,* for which the name
Fernvale was proposed, from the town of Fernvale, in William-
son county, Tennessee. From the similarity of the fossils in
the two areas this limestone overlying the Kimmswick forma-
tion in the vicinity of Thebes is considered the equivalent of
the Fernvale beds in Tennessee, and the name of the Tennessee
locality has been used to designate this basal Richmond forma-
tion in Alexander county.
This horizon is exposed at only two points, at each of which
the area of outcrop is very limited in extent. A thin zone
may be seen on the top of the Kimmswick blocks in the bed
of the river, one-fourth mile north of Thebes. A thickness of
three and one-half feet of this limestone occurs immediately
underlying the Thebes sandstonet in the south part of the
town of Thebes.
Among the fossils found in this hmestone are bulbous eri-
noid segments, Dinorthis subquadrata, Hebertella insculpta,
LH. occidentalis, Platystrophia acutilirata, Plectorthis whit-
jieldi, Rajfinesquina alternata, Rhynchotrema capax, Stropho-
mena fluctuosa and S. planumbona.
Correlation.—The continuity of the Richmond sea in IIli-
nois and Jowa was apparently broken by a number of low
land barriers extending in a general northeast-southwest direc-
tion. The sediments of this age in Jowa and northwest [li-
nois have been called the Maquoketa beds. The sea in which
they were laid down was not broadly connected with that in
which the Richmond beds in the southern and eastern parts of
the state were deposited. For this reason exact correlation of
horizons in the two areas is as yet difficult.
In the Maquoketa beds of Fayette county,t lowa, Rhyncho-
trema capax occurs at three successive horizons. It is found
first in the lower Maquoketa division, in beds of alternating
shale and impure limestone, a short distance above the zone
of WVileus vigilans (No. 5 of the general section on page 485
of the Fayette County report). The second appearance is in
the limestone or dolomite which constitutes the middle divi-
sion of the Maquoketa beds, while the third occurrence is in the
alternating shale and limestone layers near the top of the
upper Maquoketa beds. Among the fossils associated with
Lthynchotrema capax in the lowest horizon are Dinorthis sub-
-* Ulrich and Hayes; The Columbia Tennessee Folio, No. 95, U. S. G.S.,
1905.
+t Note: The position of this horizon is immediately below 2a of the gene-
ral section given in the preliminary statement. (This Journal, vol. xxv, p.
445, 1908.) It was not noted in that paper because its presence had not
been detected, nor had it previously been recognized in this portion of the
state.
{Savage : Iowa Geol. Surv., vol. xv, pp. 484-486.
514. 7. EF. Savage—Ordovician and Silurian Formations.
guadrata, Hebertella insculpta, Plectorthis whitfieldi, Stro-
phomena fluctuosa and S. planumbona. Only one of these
recurs in either of the higher horizons. From these consider-
ations the Fernvale formation of southern [llinois is thought
to correspond, in time, with the lower Rhynchotrema capax
horizon of the Maquoketa beds in Fayette county, Iowa.
Outside of this region the Fernvale formation is known in
Illinois from Monroe county; and it has also recently been
recognized by the writer in the vicinity of Millsdale, and again
two miles further north, in Will county.
The Post-Hernvale Unconformity.
The presence of an unconformity between the Fernvale
limestone and the overlying sandstone is shown in the fact
that at some points in adjacent portions of Missouri the Thebes
sandstone formation rests upon the weathered surface of the
Kimmswick beds, the Fernvale strata being entirely absent.
A considerable movement is also indicated in the change from
the limestone strata of the Fernvale to the sandstone of the
succeeding formation.
The Thebes Sandstone.
The name “ Thebes sandstone” was given by Worthen to.
the chocolate-colored sandstone and sandy shale which is well
developed and favorably exposed in the town of Thebes. The
formation is separated by its lithology and fauna, and also by
an erosional unconformity, from the Fernvale limestone upon
which it rests, and from the overlying calcareous shale. In
its lower part the strata consist of a few feet of fine, slightly
shaly sandstone, above which the beds become more massive
and the texture more coarse. In the upper portion the mate-
rial weathers into thin flakes or flaglike layers, and contains a
small admixture of shale. The thickness of the formation is
about 75 feet. ‘This sandstone carries a meager fauna. In a
narrow zone near the base trilobite fragments are very abun-
dant, but throughout the greater portion of the thickness an
occasional shell of Lingula covingtonensis, and branches of
Climacograptus putillus are the only fossils that are encoun-
tered.
The Thebes sandstone is exposed over a much larger area in
this region than any of the preceding formations. It has also
recently been found to have a much wider distribution in the
state than was formerly supposed.
The Post-Thebes Unconformity.
Evidence of a break in sedimentation closing the deposition
of the Thebes formation appears in the abrupt change in the
——
T. E. Savage—Ordovician and Silurian Formations. 515
lithology, and in the fauna, in passing from the Thebes sand-
stone to the succeeding deposits. It is shown in a strongly
weathered and iron-stained zone at the top of the Thebes
formation ; and in the fact that in different exposures the suc-
ceeding deposits rest upon different levels of the Thebes sand-
stone. |
The Orchard Creek Shale.
The name Orchard Creek shale is here proposed for a bed
(=2b of my generalized section of 1908) of calcareous shale
exposed in the banks of Orchard creek, about two miles south of
Thebes. The formation is embraced between the Thebes sand-
stone below and the Girardeau limestone above. The material
consists of bands of bluish-gray shale, four to six inches thick,
alternating with two- to four-inch layers of impure, concre-
tionary limestone. The maximum thickness of the bed is
about twenty-two feet.
An exposure of this shale, underlying the Girardeau lime-
stone, may be seen near the mouth of Orchard creek above
mentioned. It appears, above the Thebes sandstone, along the
bank of the river, and in the cut along the Chicago and East-
ern Illinois railroad, between Thebes and the village of Gale.
The more characteristic fossils of this horizon are Cyclo-
cystoides cf. ilinoisensis, Phylloporina granistriata, Dal-
manella meeki, Lepteena rhomboidalis, Lafinesquina alternata,
Lehynchotrema cf. inequivalve, Strophomena near incurvata,
Lygospira recurvirostra, Cornulites tenuistriata, Conradella,
ambricata, Pterinea thebesensis and [sotelus sp.
More than one-half of the species certainly identified from
this formation have not been reported froin any other locality.
A number of them are recurrent Mohawkian forms. The
fauna lacks the characteristic Richmond fossils, but the pres-
ence of earlier types is not unusual in the Richmond strata.
The position of these beds, above the Fernvale and the Thebes
sandstone, refers the horizon certainly to the higher Richmond.
The Post-Orchard Creek Disconformity.
No well marked line of unconformity separates the Orchard
Creek shale from the overlying Girardeau limestone. How-
ever, such a sedimentary break is indicated by the great differ-
ence between the faunas of the two formations. Out of
sixteen species collected from the Orchard Creek shale and
twenty-seven species from the Girardeau limestone, only three
are common to the two horizons. These are Leptena rhom-
boidalis, Cornulites tenwistriata and Pterinea thebesensis, all
long-ranging species. This almost total change in the fossils,
accompanied by no abrupt change in the lithology, is con-
516 LZ. FE. Savage—Ordovician and Silurian Formations.
sidered deciding evidence of a land interval between the time
of deposition of the respective beds.
SILURIAN SystTem—ALEXANDRIAN SERIES.
The term Alexandrian Series has been proposed* to include
those strata which more or less completely bridge the interval
between the uppermost horizon of the Richmond and the
basal deposits of the Clinton. They carry faunas intermediate
in character between the Richmond and the Clinton, but not
distinctively those of either group.
The formations in southern Illinois that contain faunas
which cannot properly be referred to the Richmond below, or
the Silurian above, but which have affinities in both directions,
are: 1,the Girardeau limestone, and 2, the Edgewood formation.
The Girardeau Limestone.
Strata of this age were first described by Shumard,f in 1855,
from Missouri under the name Cape Girardeau limestone.
Worthen recognized the horizon in southwest Illmois and
retained Shumard’s name for the formation.
The rocks consist of dark-colored, fine-grained, compact,
brittle lLmestone, in imperfectly separating layers two to five
inches thick. Between the layers occur thin lenses of hard,
calcareous shale which locally contain numerous fossils. Among.
the common species are Glyptocrinus fimbriatus, Tanaoert-
nus ct. typus, Camarotechia scobina, Dalmanella near
elegantula, Homeospira sp., Leptena rhomboidalis, Rafines-
guina mesacosta, Schuchertella missouriensis, Waldheumaa (?)
bicarinata var., Cyclonema cancellata, Platyostoma niagar-
ensis var., Cyrtodonta primogenia, Pterinea thebesensis,
Acidaspis halli, Cyphaspis girardeauensis, Enerinurus del-
tordeus and Lichas sp.
The maximum thickness of the formation in Illinois is
about thirty-three feet. The strata are well exposed in the
banks of a creek two miles south of Thebes, and also along
the river one-half mile further south. North of Thebes they
outcrop along the Chicago and Eastern Illinois railroad, one-
half mile south of Gale.
The Girardeau a transition fauna.—The fauna of the
Girardeau limestone, listed above, has a decidedly Silurian
aspect. The genera Homeceospira, Schuchertella, Waldheimia ?
and Platyostoma are distinctively Silurian, while not one of
the species could be considered a marker of a Richmond
horizon. A few of the Ordovician forms persist, but the
* Savage: This Journal, vol. xxv, p. 484, May, 1908.
+Shumard, B. F.: 1st and 2d Ann. Repts. Geol. Surv. Mo., p. 109, 1850.
T. E. Savage—Ordovician and Silurian Fornations. 517
presence of new Silurian types in the fauna is of much greater
significance than the lingering of a few Ordovician species.
Hence the formation is thought to represent early Silurian
time.
Although the fanna of the Girardeau limestone shows
distinctly Silurian characters, it cannot be assigned to any
recognized horizon in the Clinton. The Sexton Creek beds,
which in this region succeed the Edgewood formation overly-
ing the Girardeau, are thought to represent a Clinton horizon as
low as any previously described. Hence it seems most condu-
cive to a clear statement of the facts to refer the Girardeau and
the succeeding Edgewood formation to a distinct time interval
earlier than the Clinton, called the Alexandrian, by which the
post-Richmond and pre-Chnton age of the beds, as shown
by their stratigraphic position and by the transitional character
of the faunas, is clearly indicated.
The Post-Girardeau Unconforniity.
Clear evidence of an erosion interval succeeding the deposit
of the Girardeau limestone appears in an exposure in the bank
of the river three-fourths mile south of Gale. The strata here
which are next younger than the Girardeau limestone rest on
the very basal portion of this formation, three feet above the
top of the Orchard Creek shale. That a considerable thickness
of the Girardeau limestone was originally present here is
shown in the fact that at a distance of only twenty rods north
a thickness of thirteen feet of this limestone is exposed, and at
a less distance to the south a ledge, apparently in place, may
be seen in the river bank to a height of five and six feet.
The Edgewood Limestone.
The name Edgewood limestone is here applied to the strata
in this region lying above the Girardeau limestone and below
the Sexton Oreek formation. In my paper of 1908 these are
referred to as beds 3b and 3c. The name is taken from the
town of Edgewood in Pike county, Missouri, near which place
occur strata that have furnished fossils of this horizon in great
abundance. In Alexander county the Edgewood beds are
exposed in the bank of the river three-fourths mile south of
Gale, where they occupy a channel eroded in the Girardeau
limestone. A thin band of this limestone may also be seen
in an abandoned quarry, one-fourth mile southeast of Gale.
At the former locality there is a conglomerate at the base,
composed of fragments of Girardeau limestone. This is suc-
ceeded by a few feet of fine-grained limestone, and dark,
calcareous shale. At the top is a massive layer of hard, gray,
518 7. EL. Savage—Ordovician and Silurian Formations.
coarsely granular limestone, four feet in thickness, which is
locally oolitic in the upper part. ,
The dark shalemember furnished the fossils Clorinda sp.,
Lafinesquina mesacosta, coarsely plicate shells of Schuchertella
subplanus, and Dalmanites danw. The massive upper layer
yielded Clathrodictyon vesiculosum, Atrypa putilla, Clorinda
sp., Leptena rhomboidalis, Rhynchotreta thebesensis, Schu-
chertella subplanus, Spirifer cf. sulcatus, Whitfieldella
billingsana, Pterinea thebesensis, Dalmanites sp., Pretus
determinatus and Lichas clintonensis. The exposure in the
abandoned quarry, near Gale, furnished the following addi-
tional species: Calapecia sp., Lyellia thebesensis, Atrypa
margunalis, Plectambonites transversalis and Lhynchonella
Janed.
The Post-Edgewood Unconformity.
A break in sedimentation between the Edgewood and the
succeeding deposits is shown at the abandoned quarry, near
Gale, where the Edgewood limestone is separated from the
basal portion of the Sexton Creek beds by a two-inch band of
red, residual clay.
THe Niacaran (CLINTON) SERIES.
Seaton Creek Limestone.
The name Sexton Creek limestone is here proposed for
Silurian strata in this region, which represent some portion
of the Clinton time. The name is taken from Sexton creek,
one and one-half miles north of Gale, in Alexander county,
along which stream these beds are well exposed. In my
paper of 1908 these beds are referred to as 4a, 4b, and 4e.
Ulrich* has proposed the name Bainbridge limestone for
the Silurian strata appearing in the river bluffs for some miles
above and below Bainbridge, Missouri. He states that it is
nearly the equivalent of the Clifton limestone of Tennessee
(later than Clinton), and that it also occurs in the vicinity of
Thebes, Illinois. The present studies have shown that the
Silurian strata in the vicinity of Thebes are of Clinton age,
or earlier, and hence cannot be correlated with beds in
Missouri representing the horizon of the Clifton limestone in
Tennessee.+
The lower part of the Sexton Creek formation consists of
hard, gray limestone, in layers four to eight inches thick, which
are separated one from another by two- to four-inch bands of
* Ulrich: Mo, Bur. Geol. and Mines, vol. ii, 2d series, pz 110, 1904.
T. FE. Savage— Ordovician and Silurian Formations. 519
chert. This chert-bearing phase is succeeded by thicker layers
of pink or reddish, mottled, suberystalline hmestone.
In the upper part the cherty lmestone contains /avosztes
Javosus, Halysites catenulatus, Atrypa marginalis, Orthis
flabellites, Plectambonites transversalis, Stricklandinia triple-
siana, Triplecia ortoni var. and Lllenus cf. daytonensis. The
strata are well exposed along Sexton creek, one and one-half
miles north of Gale. They appear in the river bluff
between Gale and McClure ; and they may alsv be seen in the
bank of the river two and one-half miles south of Thebes. The
maximum thickness of the formation is about seventy feet.
The species of fossils listed above indicate that the Sexton
Creek limestone represents the westward extension of the
Olinton strata occurring in Indiana and Ohio.
The Post-Sexton Creek Unconformity.
After the deposition of the Sexton Creek beds, land condi-
tions prevailed over this area for the greater portion of the
time during which the Niagara limestones in the northern por-
tion of the state were laid down. The strata that occur next
above the Sexton Creek beds, in this region, represent the
Helderbergian series of the Devonian.
Oscillations of level.Frequent strand-line movements are
clearly recorded in the Coal Measure deposits of [linois, and
elsewhere, where a number of coal seams occur in vertical sue-
cession, and separated one from another by marine beds of
shale or limestone. The numerous oscillations that are shown
to have occurred in southwest Illinois, during the late Ordovi-
cian and early Silurian times, would indicate that frequent
movements were not peculiar to the Pennsylvanian Period.
It seems probable that oscillations of level may not have been
uncommon throughout the Paleozoic era. The scarcity of such
records may be largely due to the fact that the deposits made
in shallow water, near shore, are not present over large areas ;
and that such deposits would be most likely to be removed
during subsequent periods of erosion.
University of Illinois, Urbana, I11.
520 Ff. M. Kindle—Section at Cape Thompson, Alaska.
Arr. XLVIII—7he Section at Cape Thompson, Alaska;*
by E. M. Kryptz.
Introduction.
Care THompson is a promontory on the Arctic coast: of
Alaska, located about 125 miles uorth of the Arctie Circle.
It is one of a series of bold headlands which face the sea with
vertical cliffs 400’ to 700’ high for 6 or 7 miles immediately
south of the delta and shore line deposits which lie about the
mouth of the Kukpuk River. Alluvial deposits broken by
lagoons form the coast line for about 40 miles northwest of
Cape Thompson, where the coast line is again formed by
cliffs and precipitous hills which continue northward to Cape
Lisborne. This portion of the coast is not visited by any of
the passenger vessels engaged in Alaskan transportation, but
through the courtesy of the officials of the U. S. revenue
cutter service and of Capt. Henderson of the revenue cutter
Thetis, the writer was enabled to spend a few days during the
past season studying the geological section exposed in the
vicinity of Cape Thompson. The writer’s brief shore leave
permitted only the study of the rocks in the immediate vicin-
ity of Cape Thompson and a short trip up the Kukpuk River.
Mr. R. D. Mesler assisted the writer in the field work.
Acknowledgments are due to Mr. Jos. Tuckfield and Mr. Jas.
Allen, residents of Point Hope, for their nnbounded hospital-
ity. The writer’s special thanks are also due to Mr. W. Allen
Richardson, teacher of the native school at Point Hope, and
Dr. John B. Driggs, the veteran missionary, for courtesies
extended, and to Capt. White for transportation on the schooner
South Bend.
Previous Geologie Investigations.
The geological section at Cape Thompson was examined in
1826 by Mr. A. Collie of Capt. F. W. Beechey’s exploring
expedition. Lieut. Belcher of the expedition prepared a sec-
tion of the strata observed, and Mr. Collie collected fossils
which led Prof. Buckland to correlate the limestone with the
Derbyshire limestone of England.t It thus appears that this
extremely remote section was one of the first on the continent
to be correlated with European sections.
The results of Capt. Beechey’s expeditions were summarized
by Grewingk,t who states that the fossils from Cape Lisburne >
* Published by permission of the Director of the U S. Geol. Survey.
+ Zoology of Capt. Beechey’s Voyage, Bohn, London, 1839, pp. 171-172.
{ Grewingk, C., Beitrag zur Kentniss der orographischen und geognosti-
schen Beschaffenheit der Nord-West-Kiiste Amerikas mit den anliegenden
Inseln: Verhandl. Russ.-K. Mineral. Gesell. zu St. Petersburg, 1848 and ’49
1850), pp. 160-161, pp. 343-344.
E. M. Kindle—Section at Cape Thompson, Alaska. 521
obtained by them were found to be Silurian by Fisher and
Kupreanoff. At a much later date a brief note on a slab of
fossils from Cape Thompson appeared in a report by Prof. A.
Hyatt. These were considered to be “ probably Triassic”* by
Prof. Hyatt. In 1896 Mr. Chas. Schuchert included in his
“ Report on Paleozoic fossils from Alaska”’+ a single species—
Spirifer condor, which was found on the beach near Cape
Thompson by Mr. W. J. Fisher. A. J. Collier published in
1906 a sketch of the section at Cape Thompson as seen from
a steamer in passing the Cape.t
Although mentioned, as noted above, by various subsequent
writers, little has been added to the information furnished by
Mr. A. Collie’s notes published more than three-quarters of a
century ago.
The unaltered condition of the rocks here affords excep-
tional opportunities to secure perfectly preserved fossils in
abundance from the Carboniferous limestone, thus eliminating
the uncertainty which frequently attaches to the determination of
fossils as they are so often found in the highly altered rocks of
many parts of Alaska.
General Geologic Relations.
The oldest rocks exposed in the vicinity of Cape Thompson
are of Oarboniferous age. Rocks of pre-Carboniferous age
doubtless underlie most of the delta deposits immediately
west and northwest of the Cape, but the outcrops of these
rocks, so far as known, do not extend far south of the channel
of the Kukpuk River. Along this stream these older rocks,
which have been provisionally referred to the Devonian by
Collier,§ are well exposed. No fossils have been found in
them. They comprise mainly black slates and shales together
with sandstones containing some volcanic material with rarely
a band of red shale. These older rocks form a belt bordering
the Carboniferous limestones on the west to the northwest of
the Kukpuk River. Although unknown by outcrops, this
belt no doubt reaches the coast beneath the shore line and
delta deposits to the west of Cape Thompson.
The rocks exposed in the vicinity of Cape Thompson include
both Carboniferous and Mesozoic rocks. The principal struc-
tural feature governing the distribution and attitude of the
rocks near the Cape isa syncline. The axis of this syncline
reaches the coast about two miles southeast of the most north-
*17th Ann. Rept., Direct. U. S. Geol. Survey, Pt. I, p. 907, 1896.
+ 17th Ann. Rept., Direct. U. S. Geol. Survey, Pt. I, p. 898, 1896.
{ Geology and Coal Resources of the Cape Lisburne Region, Alaska, Bull.
U.S. Geol. Survey, 278, p. 21, 1906.
§ Collier, A. J., Geology and Coal Resources of the Cape Lisburne Region,
Alaska, Bull. U. S. Geol. Survey No. 278, p. 17, 1906.
522 EE. MW. Kindle—Section at Cape Thompson, Alaska.
westerly outcrops near Cape Thompson, whence it trends
northerly or northwesterly. Near the middle of this syneline
along the coast, the rocks lie nearly or quite horizontal for
more than a quarter of a mile. From the horizontal they pass
eradually into the inclined position, showing dips on opposite
sides of the syncline toward its axis. These increase from five
or ten degrees nearest the center to a maximum of about 40°
on the southeast and 90° on the northwest. This synclinal
structure is expressed in the areal distribution of the rocks by
two parallel belts of Carboniferous limestone separated by a
band of Mesozoic shales one and a half or two miles in width.
Toward the south side of the syncline the transition from very
slight to steep dips is gradual and progressively uniform from
the nearly horizontal Mesozoic shales to the highly inclined
limestones, where the dip is uniformly about 35 degrees.
On the west side, however, the uniformity of the syncline
is broken up by a local anticline about 300 feet in width,
known as agate rock. This minor structural modification of
the syncline shows most intricately crumpled and broken beds
below the belt of regularly arched strata at the top, which give
it the appearance of a typical anticline when seen from a little
distance. This local fold is shown in a photograph published
by Collier.* The Carboniferous limestones comprising Cape
Thompson on the northwest side of the syncline also show
marked irregularities in dip. That these irregularities are not
evident from a distance is indicated by Collier’s+ sketch of the
section, which was made from the deck of a steamer at a dis-
tance of about 3 miles from the Cape. It indicates a uniform
westerly dip for the limestones. Nearly the same inclination
is indicated for them in the section by Lieut. Belcher of Capt.
Beechey’s expedition. Instead of a uniform westerly dip, the
beds at the Cape are generally inclined toward the east at vari-
ous angles ranging from 90° to horizontal. The most westerly
beds exposed at the Cape include about 400 feet of shales and
sandstones which dip toward the east or the axis of the syncline
already described at from 80° to 90°. The Carboniferous
limestone lying between these basal shales and the Mesozoic
beds are generally inclined where observed toward the east at
angles ranging from 25° to 90°.
Age of the Formations.
The lowest beds exposed at Cape Thompson outcrop along
the beach immediately north of the cliffs. The rocks exposed
* Collier, A. J., Geology and Coal Resources of the Cape Lisburne Region,
Alaska, Bull. U. S. Geol. Survey No. 278, pl. 4, fig. A.
+ Bull. U. S. Geol. Survey No. 278, p. 21, 1906.
¢{ Buckland, W., Geology and Zoology of Capt. Beechey’s Voyage, London,
Henry V. Bohn, 1839, pp. 171-174.
E. M. Kindle—Section at Cape T: ee Alaska. 523
in these beach outcrops and the accessible or northern portions
of the Cape cliffs are indicated by the following section :
Section 14 at Cape Thompson.
d Light buff or cream-colored limestone with numer-
ous fossils. Str. about N. S., dip variable,
mostly E. 25 to 90’, complicated toward the
ROE HROr neces. Zi UR Nie erat Sees elke Ap OOUCE
e Black and buff thin-bedded limestone, the former
predominating. Productus and large crinoid
SIENA Sau OUINC ATG.) ues a. See OR ies sane 380’
6 Bluish gray to black fissile shale with abundant
plant fragments. Dip E.80t0 90°. Str.N.15 W. 280’
a Very thin-bedded lead gray sandstone with occa-
sional bands of brown ferruginous chert and
films of coal. Plant fragments abundant. Str.
RON Dip. F86 to0 ee 140/
The lower 400 feet of the section appears to contain no
‘invertebrate fossils. All or nearly all of these beds represent
non-marine sediments. Plant remains in various stages of
maceration occur through most of the shales and sandstones
below the limestone. Plant fossils were obtained from both @
and 6 of the section and numbered respectively lots 5289 and
5290. These were submitted to Dr. David White, whose
report follows:
“Tot 5289. This lot consists of three fragments of coarse, gray
sandstone bearing carbonized impressions of pieces of par-
tially decorticated stems. The characters of the very
imperfect impressions point toward a close affinity with
Lepidodendron corrugatum.
Lot 5290. This lot includes two small packages of wavy, black
carbonaceous shale splitting in thin laminae. This shale
contains many fragments of leaves of Lepidodendron,
and unidentifiable, decorticated stem fragments of several
kinds, together with several imperfect remains in a better
state of preservation. The latter represent Sphenopteris
Jrigida Heer, twigs of Lepidodendron Veltheimianum as
generally identified in the European and Arctic floras,
with a cone fragment possibly belonging to the same spe-
cies, and portions of a Lepidophyllum very close to Lepi-
dophyllum fuisseense Vaff. ‘There are also present several
fragments of a cyclopterid type ; these are so incomplete
that it is not really possible to decide whether they repre-
sent (a) rachial pinnules of Neuropteris; (0) some large,
broad pinnuled Aneimites ; or, (c) pinnules of Cardiopteris.
I am inclined to refer them to the latter genus.
The plant remains from Cape Thompson are so fragmentary
and meager as to determinable species as not to permit a close
524. EF. M. Kindle—Section at Cape Thompson, Alaska.
determination of the age of the beds. They appear to be
Mississippian and probably represent a stage in the lower part
of this division. ‘hey may even come from the basal member
thereof.”
These plants evidently belong to the same horizon as that
from which Oollier obtained Carboniferous plants at Cape Lis-
burne. Concerning the Cape Lisburne plants, Dr. White’s
report* contains the following statement relative to their age :
‘‘These fossil plants are evidently of Carboniferous age.
Owing to the marked scarcity of filicate elements the testimony
of the collection is less direct as to precise age than might other-
wise be the case. However, from the evidence in hand I am
forced to conclude that the plant-bearing terrane is Mississipian,
and it appears probable that it is referable to the lower. portion
of the Mississippian. The flora, especially that of lot 3554, is
very closely related to that from Bell Sound and Klass-Billen Bay
in Spitzbergen. It seems to be slightly younger than the Ursa
flora.”
Above the plant-bearing beds only marine fossils are seen.
The limestones which follow the sandstone and shales carry an
abundant fauna. Oorals are quite abundant in the upper
division of the limestone series. Dr. Girty has furnished the
following list of fossils from these beds:
Wot LC.
Fenestella sp.
Cystodictya ? sp.
Derbya? sp.
Productus semireticulatus
Reticularia ? sp.
Lot 14 D.
Lithostrotion sp. A.
Crinoid stems
Kenestella sp.
Hemiirypa sp.
Stenopora sp.
Cystodictya ? sp.
Streblotrypa ? sp.
Chonetes sp.
Productus semireticulatus
Productus aff. burlingtonensis
Productus aff. concentricus
Spirifer aff. striatus
Reticularia ? sp.
Griffithides ? sp.
Bairdia? sp.
* Collier, A. J., Geology and Coal Resources of the Cape Lisburne Region,
Alaska, Bull. U. S. Geol. Survey No. 278, p. 22, 1906.
E. M. Kindle—Section at Cape Thompson, Alaska. 525
Lot Dp
Lithostrotion sp. A.
of sp. C.
ZLaphrentis sp.
Pentremites ? sp.
Fenestella sp.
Polypora sp.
Hemitrypa sp.
Cystodictya ? sp.
skeie Saas aff. setiger
“ vittatus
cestriensis
burlingtonensis
pileiformis
na .
n sN
n
n n
n
nn
nn
an
sp.
Fouad ? sp.
Derbya? sp.
Camarotoechia sp.
6é 6¢
Rynchopora sp.
Dielasma ? sp.
i ? sp.
e turgidum ?
Spirifer aff. neglectus
‘“¢ subcardiiformis
- ‘“< agelaius
S “< rostellatus
Martinia? sp.
Spiriferina aff. subelliptica
Athyris aff. incrassata
Clothyridina hirsuta ?
of rOUssus
Eumetria marcyt ?
Se ae DSP,
Hustedia? n. sp.
Platyceras sp.
Griffithides? sp.
While some of the collections are much less numerous than
others, it is probably safe to refer them to a single fauna,
which is without much question of lower Carboniferous or
Mississippian age. It is true that some of the forms appear
to be allied to species in the Burlington and Keokuk of the
Mississippian section, but I believe that the beds furnishing
these fossils should correlate only with the upper Mississippian.
Indeed, the faunas are especially suggestive of the well-known
fauna of Spergen Hill, which is known to have been rather
extensively distributed toward the northwest.
I have long been of the opinion that our upper Mississippian
correlates in a general way with the Mississippian limestone of
*D' represents the uppermost 100’ of division d of the section.
Am. Jour. Sct.—FourrtH Series, Vou. XXVIII, No. 168.—DrcrempeEr, 1909.
30
526 EE. M. Kindle—Section at Cape Thompson, Alaska.
Europe and Asia, but the evidence has been more or less indi.
rect and general in character. The present faunas are espe-
cially interesting, because they seem to show to some extent a
mingling of the two faunas. The Mountain limestone element
is represented by the abundance of Lzthostxotion, and other
features could probably be pointed out by one familiar with the
European faunas. The coral fauna of the Mountain limestone
is already known in Alaska, especially at Cape Lisburne, but
it has not there so far as known the admixture of Mississippian
types.”
on connection with the interesting resemblance of the Cape
Thompson fauna to the Spergen Hill fauna pointed out by Dr.
Girty, reference may be made to the minute character of many
of the brachiopods occurring at horizon 14 D’. In this feature
the fauna strikingly resembles the depauperate Spergen Hill
fauna. The presence im the fauna of a small specimen of Pen-
tremites or a closely allied genus is also worthy of note in this
connection. Although extremely abundant in the Mississippi
valley, this blastoid has been recognized at but two localities in
the Rocky Mountains, and in both of these occurrences it is
associated with a fauna closely resembling the Spergen Hill
fauna.
The higher beds of the Cape Thompson section are brought
in contact with the beds already described in the midst of a
zone of rather local but complicated folding and possibly of
faulting, which renders it impossible to give even an approxi-
mate estimate of their thickness as seen from the top of the
southeastern portion of the Cape Thompson ciifis; but between
the second and the fourth deep ravines separating the high
ridges just southeast of the cape along the coast the exposures
are continuous for two miles, exposing a section of northerly
dipping beds in which the dip decreases from 35° to O near
the middle of the synclinal. We find in the series of cliffs
which face the sea to the southeast of the second ravine below
Cape Thompson a section which passes without structural
complications from the fossiliferous Carboniferous limestones
to the top of the highest beds exposed in this vicinity. This
section is as follows; |
Section 15, two miles southeast of Cape Thompson.
é Soft blackishales@ 226-2234 — eee ee eee 500 +
d Dark cherts and thin-bedded cherty limestones
with some greenish bands —-_2 -22 122. --22 222 25'
e Argillites with bands of black, green and dull red
cherts -. 2). py See ee eee 600’
6 Light gray limestone weathering buff, with some
bands of dark chert. Apparently barren of fos-
Sils 022i lke 2 ee
a light gray limestone similar to the above, but with
less chert and containing numerous fossils in
which corals are conspicuous _-.-..---.-- ---- 3000'+
E. M. Kindle—Section at Cape Thompson, Alaska. 527
In the upper part of the lowest division of this thick lme-
stone series, @ of the section, fossils are fairly abundant, and
represent about the same species as found at14 D’. Only a
few were collected, however. These are given in the follow-
ing list by Dr. Girty, whose remarks on the general faunal
relations of these faunas have already been given.
‘Lot iscA:
ZLaphrentis sp.
Spirifer aff. striatus
Composita ? sp.
The close physical resemblance of the second division (6) of
the limestone series to the lower leaves little doubt that it is also
of Carboniferous age. It may represent the Upper Carbonifer-
ous, which has not been recognized anywhere on the north-
western coast of Alaska, though known on the Yukon and in
southeastern Alaska.
The lithologic change at the top of this limestone series is
abrupt. The ‘beds included in ¢ and d are essentially similar,
and represent the same formation, although there is less of the
calcareous element in the lower beds. Fossils were found,
however, only in the upper beds marked d@ in the section.
They occur in great abundance in certain strata in this portion
of the section. About seven feet near the top are composed
almost exclusively of shells which have been largely altered to
chert. Dr. T. W. Stanton has furnished the following report
on the fossils secured from this horizon :
“Lot 15d. Mouth of creek 2 miles southeast of Cape Thomp-
son.
This collection consists of limestone fragments with numerous
specimens of aviculoid shells referable to Psewdomonotis subcir-
cularis (Gabb) or to a closely related species. No other recogniz-
able species are associated with it. This species occurs in an
Upper Triassic horizon in California, and it has been accepted as
sufficient evidence for the Triassic age of rocks containing it at
Cold Bay and in the Copper River region of Alaska. In my
opinion, the horizon which yielded it at Cape Thompson is also
Upper Triassic.
Among the collections obtained by Mr. Collier in the Cape Lis-
burne region some years ago there are several small lots consist-
ing mainly of a form that seems to be identical with Psewdomo-
notis subcircularis and probably comes from about the same
horizon as this Cape Thompson locality. These fossils were at
that time identified as Aviculopecten and referred to the Carbon-
iferous, chiefly because of the stratigraphic relations they were
supposed to hold with well-characterized, Carboniferous faunas.
If Mr. Kindle’s interpretation of the structure is correct the hori-
528 ff. M. Kindle—Section at Cape Thompson, Alaska.
zon in question at Cape Thompson is above all the Carboniferous
faunas and offers no stratigraphic difficulties in its reference to
the Triassic.”
The fossils in Collier’s collection alluded to above as having
been included in the Carboniferous fauna appear in the lists
published by him as faunules composed exclusively of lamelli-
branchs and with one exception showing no associated species
which would point definitely to their Carboniferous age. This
exception is the faunule of station 4 A C 16,* and it includes
in addition to Aviculopecten ? sp., Productella sp., Reticularia
sp., Pretus sp., etc. Examination of these fossils shows that
the Aviculopecten of this faunule is an entirely different shell
from the “‘ Aviculopectens” of the other faunules, which con-
tain only “ Avzculopectens.” It does not, therefore, connect
the faunules composed almost exclusively of the latter with an
undoubted Carboniferous fauna, as Messrs. Collier and Wash-
burne, who collected the fossils, supposed it did. With refer-
ence to the stratigraphic evidence of the superposition of Car-
boniter ous limestone above the beds containing “ Avzculopec-
ten” (Pseudomonotis subcircularis) in the Cape Lisburne
region, it may be remarked that the region is one in which
faulting is a common and characteristic feature, and one,
therefore, in which present superposition might not represent
the original relations of the beds.
The beds containng Pseudomonotis subcircularis at Cape
Thompson and the 500 feet or more of soft shales above them
lie nearly horizontal for about half a mile to the south of the
anticlinal arch known as Agate Rock. The belt of territory
underlaid by these softer horizontal beds is°a valley region
broken up by ravines and bordered on each side by an elevated
limestone ridge and moderate-sized hills. If the shales were
followed by any thick limestone formation, its presence should
be manifested in the topography, but there is no such evidence
of any limestone series above the flat-lying shales. The soft,
black shale comprising the highest subdivision of this section
contained no fossils where examined by the writer, and we
are without definite evidence -as to whether it should be
assigned to the Triassic or Jurassic. The resemblance of the
carbonaceous shales comprising it to portions of the Corwin
formation as described by Colliert near Cape Lisburne suggests
its provisional correlation with that formation.
* Bull. U. S. Geol. Survey, No. 278, p. 23, 1906.
+ Collier, A. J., Geology and Coal Resources of the Cape Lisburne Region,
Alaska, Bull. U. S. Geol. Survey, No. 278, pp. 27-28, 1906.
Hutchins—New Method of Measuring Light Lificiency. 529
Arr. XLIX.—A New M ethod of Measuring Light Efficiency;
by C. C. Hurcuins.
THE measurement of light efficiency has been attended with
unusual difficulties considering that what is required is merely
the ratio of two numbers representing respectively the values _
of the visible and total radiation of the source. Nor do the
difficulties arise merely from the necessity of comparing large
things with small, but rather for the want of some method of
properly separating the quantities to be compared.
To obtain a complete energy curve, and to compare the
integral of the visible portion with the total is an, extremely
tedious and somewhat uncertain procedure. Angstrém’s
method requires an elaborate apparatus and the application of
several troublesome corrections.
It is believed that the following method will be found as —
accurate, and much more simple and direct than those hitherto
in use,
Theoretical.—Let the figure represent the energy curve of
the light source; the vertical line separating the visible (qa),
from the intra red (6). If now we define efficiency as the ratio
of the visible to the total radiation, we have:
a
GEO.
efficiency =
' Let now a water cell a few millimeters thick be placed in
the path of the light. Assuming for the moment that the
water is perfectly transparent to light; @+c¢ becomes the trans-
mitted energy, the curve coming down to zero at wave length
1°8y.
530 Hutchins—New Method of Measuring Light Efficiency.
Further let a cell identical with the water cell, but contain-
ing a water solution opaque to light but transmitting more or
less infra red, be interposed: and let the transmitted energy
be d. The transmission curve d must lie within the same nar-
row limits with ¢ and the two areas be strictly comparable
under like conditions.
If now we can measure a+b, a+c, d, and the ratio of ¢ to d
we have all that is required. For let
Goda) == 70
Ge Ce — tae
C =
a Ii
then yak a = ee a
atb n
Apparatus and Methods.—A thermopile consisting of a
single junction at the focus of a small concave mirror set in a
proper tube with diaphragms is pointed at the light and expo-
sure made by moving a double wooden shutter. The deflec-
tion of the galvanometer is reduced by a known amount by
putting resistance in the circuit. The deflection so obtained
is proportional to 2.
A water cell about 5"™ thick, having thin plate-glass walls,
is then placed behind the shutter; the resistance is removed
from the circuit, exposures made as before, and we obtain
deflections proportional to m.
For obtaining d, a preliminary study of a large number of
substances showed potassium permanganate to be quite suit-
able. It is very strong in color in solution, may be made
opaque to sunlight in a thin layer, while transmitting a con-
siderable amount of infra red. A duplicate of the water cell
is filled with a solution of permanganate of such strength as
to just show the light under me esie BEL OM, when held between
the light and the eye.
This cell being substituted for the water cell, we obtain a
deflection pr oportional to d.
To find the ratio 7.
A spectroscope was given the following additions. A long
slit was put in the place of the ordinary short one. The eye-
piece was removed and replaced by an ebonite screen having
a rectangular opening. One edge of the opening was cut to
fit the curve of the spectrum lines in the red. The spectrum
of the light source is focused upon the screen and the tele-
scope adjusted so that the visible spectrum is just cut off by
the curved edge. The infra red alone now appears in the open-
ing. In this position the telescope is firmly clamped.
Hutchins—New Method of Measuring Light ficiency. 581
Over the eye end of the telescope is now slipped a tube,
having at its farther end a concave mirror and thermal junc-
tion. ‘The mirror is large enough to receive the entire cone of
rays coming through the screen, and condenses them upon the
junction at its focus. This arrangement was used because it was
at hand; a thermopile or bolometer, having a suitable receiv-
ing surface, placed immediately behind the screen, would be
simpler. An image of the light source being thrown upon
the sht of the spectroscope, the water and permanganate cells
are placed alternately against the objective of the collimator ;
a shutter is moved as before, and the attached galvanometer
gives deflections proportional to ¢ and d respectively.
Remarks upon setting the screen.—lt has been customary in
determinations of hghit efficiency to assume some definite limit
to the visible spectrum, as °76 w. Such a limit is quite useful
for purposes of uniformity, that one man’s work may be com-
pared with another’s, but only roughly corresponds to fact
except in the case of sunlight. The limit of the spectrum is
not the same for all lights or all eyes. It would therefore seem
more logical to set the screen upon or near the limit of the red of
the light under examination, although this will commonly give
a smaller value for the efficiency than that obtained from °76 pw
asa limit. This procedure seems further justified when we
observe how steeply the energy curve rises at the limit of the
red; so that a very slight movement of the screen upwards
in the spectrum diminishes the apparent efliciency largely,
while the actual light is diminished by an _ inappreciable
amount. The smaller values therefore more manly represent
the practical efficiencies.
Example of the method.—The following measurements were
made upon a portable acetylene lamp in which the gas is gen-
erated by automatically feeding granular carbide into water
contained in the base of the lamp. ‘The feed being intermit-
tent, the light varies considerably but a fair average could be
obtained by distributing the readings over a considerable time.
The resistance of the galvanometer and circuit is 2°203 ohms.
Through water the mean of 5 deflections was 202°2 milli-
meter divisions. ‘Through permanganate 45:0 divisions. Ten
ohms were added to the circuit, and the lamp direct gave
250°6 div., which when reduced to the -scale of the others
becomes 2531.
With the prismatic apparatus the mean of 20 readings
through water with 4 ohms in circuit was 293-7. The resist-
ance of the circuit is 2 203, and the deflection without added
resistance reduces to 827:0.
The mean deflection through the permanganate cell was
205°8
5382 Hutchins—New Method of Measuring Light Efficiency.
From these readings we have
We ==) LOL dr = 1¥80°9
Oh == QE m — dr = 39°3
d = 45:00 m — dr = ‘0263
== ASO28 ”
This result is subject to a plus correction of 13 per cent
because of the loss of light to that amount in passing through
the water cell. Applying this correction, we get -0296 for
the light efficiency.
A second determination made after resetting the screen and
changing the sensibility of the galvanomter gave 0323. The
mean of the two is ‘0309 and the departure from the mean
6 per cent. The result may be considered very satisfactory
considering the large change in apparent efficiency produced
by a small displacement of the screen.
Nichols and Coblentz* found -033 from integration of the
energy curve of a cylindrical acetylene flame, and 030 from a
comparison of the transmission curve through water and
iodine in bisulphide of carbon.
Bowdoin College, Oct. 30, 1909.
* Physical Review, Oct. 1903.
S. A. Rohwer—Three New Fossil Insects. 533
Art. L.—TZhree New Fossil Insects from Florissant, Colo-
rado;* by 8. A. Ronwer, Boulder, Col.
Raphidia mortua n. sp.
Sex doubtful: length of the anterior wing, 10™™ ; width of
the anterior wing, 3"; length of the meso- and metathorax and
abdomen about 8™. Color brown, the thorax darker, legs
except one tibia, which is pale, wanting; the head and pro-
thorax are wanting. The venation is pale brown. Costal area
large, with six cross-veins. Subcosta straight, joining the costa
at about the length of the stigma from the stigma. The area
between the subcosta and the radius crossed by at least one
distinct cross-vein ; this cross-vein is not interstitial with any of
the cross-veins of the costal area, and would form an obtuse
angle with them. Stigma at the base perpendicular, about
equal in width throughout, crossed by an oblique vein ; the vein
at the apex is curved basally so that the end of the stioma is
concave. The first cell below the stigma extends bey ond the
cross-vein of the stigma, but does not extend beyond the apex of
the stigma. The cell below this is as in Raphidia oblita. The
terminal veinlets form six V-shaped cells. The hind wings are
about the same length as the fore wings. Besides the usual differ-
ences the stigma is broader where the cross-vein joins it, and
there are only three V-shaped marginal cells. The following.
measurements of the fore-wings are in micromillimeters:
Distance of the cross-vein from the apex of the stigma on
iy DEY CSCS ae RN SS eg ee cae Rng ne 935
Distance of the cross-vein from the base of the stigma on
SME COS Is ne RNS RAL LME LA iby EADY ne is SEUSS se 850
Distance of the cross-vein from the apex of the stigma on
BERG AND Inset te ee ho Uh IRR Tc ea NS Go
Distance of the cross-vein from the base of the stigma on
PCR CAML NUES eaters meee) DEie Ss Te Ve ea. TS pat a oh et ae 425
Distance of the apex of the stigma from the apex of the
Se ClOW Tie k attoe at eee ees Pe A RA Re eR OG
Distance from the base of the stigma to the subcosta.... 850
Length of the cross-vein of the cell between the subcosta
MERIT: EAC 2p aA ease, Re ah Sa ek ee ee OT
The venation of this eae is very different from that of
Laphidia notata (fig. 2, Pl. 5, Lief. I, Fossilen Insekten),
which has the subcosta ae the costa at the base of the
stigma.
If compared with the venation of Leaphidia oblita as tigured
by J. F. McClendon in the Ent. News, xvii, April, 1906, p. 117,
* Thanks are due to Prof. T. D. A. Cockerell for the pleasure of studying
these interesting fossils, and for going over my manuscript.
534 S. A. Rohwer—Three New Fossil Insects.
the following differences will be noted: The subcosta is at a
greater distance from the stigma. The apex of the stigma
is concave. There are fewer cross-veins in the costal
area. The ecross-vein between the subecosta and the radius is
not interstitial with a cross-vein of the costal area. The cells
below the stigma are shorter. The cell bounded above and
below by R, and R, (= RS) is pentagonal not hexagonal.
Of all the fossil species it seems nearest to /nocellia tumulata
Seudder, but it differs from that species in having a cross-vein
in the stigma; the cell below the stigma reaches beyond the
middle of the stigma; the space between the subcosta and the
costa is transversed by a number of cross-veins.
Habitat: The Tertiary shales of Florissant, Colorado, col-
lected in 1908 by George N. Rohwer at Station 14. ‘Type in
the collection of the University of Colorado.
The following table of the fore wings of certain species,
both fossil and recent (the recent ones are starred), is interest-
ing in that it shows the relation of the fossil and recent fannee ;
and useful in that it'separates the species of fossil Raphidia
found at Florissant. As Dr. Scudder has given a table of the
species of /nocellia they are not included.
Subcosta joining the costaat the base of the stigma .--. notata*
Subcosta joining the costa remote from the stigma -.- - ]
1. Stigma without a scross-weln _.._._.-.--2 ._) = =e@cammm
Stigma with at least one cross-vein _-._.------..- 2
2. R, with but one branch beyond the stigma .------ 3
R, with two branches beyond the stigma --.---.---- 6
3. The costal area very small and apparently without
cross-veins ; the subcosta forming most of the mar- .
gin of the wing ; stigma “small, semi-oval” St. (?) tranguilla
The costal area not small and with distinct cross-veins 4
4. The first cell below the stigma not extending beyond
the stigma LR. mortua
The first cell below the stigma extending beyond it 5
5. The cell bounded by R, and R, (= RS) pentagonal
R. rhodopica*
The above mentioned cell hexagonal _--.-------- Rh. oblita*
6. R, not forked ; length of the anterior wing 12™™ &. exhumata
R, forked ; the anterior wing 14" __ Megaraphidia elegans t
Chrysis miocenica n. sp.
Female: length of the thorax, 6™ ; length of the head, 2™™ ;
length of the abdomen, 8™™; length of the anterior wing, 7°5™™,
+ For further differences between R. exhumata and M. elegans see Bull-
Am. Mus. Nat. Hist., 1909, p. 73. In the figure of M. elegans (Bull. Am.
Mus. Nat. Hist., 1907, p. 607) the artist has omitted the costal area. and has
drawn R, incorrectly, with one instead of two branches beyond the ptero-
stigma. The cross-vein below the stigma is too far from the end of the
latter.—T. D. A. C.
S. A. Rohwer— Three New Fossil Insects. 535
The head is not longer than the thorax. The malar space is
distinct ; the eyes oval. The flagellum is about two and a
half times as long as the scape; the first joint of the flagellum
is distinctly longer than the second and the second is a little
longer than the third. The legs are rather more robust than
usual. The venation is rather weak, and normal, differing from
C. (Gonochrysis) densa Oresson only in that the radius rises
nearer the middle of the small stigma. The abdomen is as long
as the head and thorax combined. The apical teeth cannot be
seen, but from the general appearance the insect suggests Gono-
chrysis. The ovipositor is exserted, and is rather more robust
than usual, length 2°75". In the specimen the sculpture can-
not be seen, but it is undoubtedly punctured as in the recent
Species of to-day.
Habitat: The Tertiary shales of Florissant, Colorado, at
Station 14. The collector is unknown. The type is im ‘the
University of Colorado.
The only other fossil Chryszs from Florissant is C. rohweri
Ckll., which differs from the present species in its much smaller
size, aud the abdomen is shorter than the head and thorax.
Ohra ysis mortua is in general appearance like the recent species
densa Oress. found at Florissant to-day. It is however much
larger than any specimen of densa known to me.
Philanthus saxigenus n. sp.
Sex doubtful; length of the head and thorax and first two
abdominal segments, 9°5"™; length of the anterior wing, 8°75".
Head about the same width as the thorax; ocelli in a low
triangle; the lateral ocellus about 204 in diameter. Thorax
subquadrate, 4°5"™ long, and at the wings 4°5™™ wide. The
head and thorax finely sculptured; the mesonotum with two
slightly converging grooves near the center; these grooves
extend posteriorly to about the hind wings; a little above the
tegule are two shorter grooves; the teoulee are rather large.
The hind tibiz are short yet not shorter than in some of the
recent members of the genus: they are not serrate or spinose
in the fossil; the spurs are shorter than the hind basitarsus;
the four anterior legs are not present in the fossil. The radial
cell is normal (attaining the costa without an appendiculation) ;
the stigma is of medium size; third transverse cubitus is
strongly bent basally about the middle ; the second recurrent
nervure is interstitial with the second transverse cubitus; the
second transverse cubitus is slightly oblique ; the first recurrent
nervure joining the second cubital cell about the middle; the
transverse median received by the discoidal cell distinctly
beyond the median. Abdomen sessile; the first segment
widening toward the apex; abdomen “beyond the second
536 S. A. Rohwer—Three New Fossil Insects.
segment wanting. Color perhaps rufous, no black markings
evident in the specimen. Wings hyaline, the venation pale
brown. The following measurements are in micromil-
limeters :—
Length of the stigma... 255.00: 222203. rr
Lene thot tbelsecond! tran) cubituss2 22.0 4-5) aes 476
Breadthof thestioma "222.005.2102 2 ee
Length of the third cubital cell on the radius._...._. 1820
Length of the second cubital cell on the radius___-_-- 935
Length of the first cubital cell on the radius___-._-- og
Length of the second cubital cell on the cubitus....._ 1105
Length of the first cubital cell on the cubitus._..__.- 1530
Distance the tran. median is beyond the basal__...--. 289
The first recurrent nervure beyond first tran. cubitus. 325
Habitat :—Tertiary shales of Florissant, Colorado. One
specimen collected by Prof. T. D. A. Cockerell at Station 9 (a
hill facing north about three-fourths of a mile southwest of the
town). The type in the University of Colorado. Many thanks
are due to Prof. Cockerell for assistance in the study of this
interesting fossil. This species is very distinct from Pro-
philanthus destructus Ckll., the only other fossil Philanthid
known from Florissant, being readily distinguished by its
smaller size and the radial cell reaching the costa. In the posi-
tion of the second recurrent nervure P. saxigenus departs from
all other species of the genus Philanthus known to me, but
this is a matter of small importance. The grooves of the
mesonotum are very similar to those of Aphilanthops fridigus
(Cress.), but it cannot be an Aphilanthops on account of the
shape of the radial cell. Phdanthus pulcher D. T. (pul-
chellus Oress.), which has been taken at Florissant, is much
like P. saxigenus, but it is smaller and the venation is difter-.
ent. Philanthus sanborni Cress. (Mass.) 1s very similar in
general habitus to saxigenus, and the specimen before me has
the second recurrent nearer to the second transverse cubitus
than in any other species I haveseen. The relative length of the
second and third cubital cells is not reliable, and I do not think
the genus Epiphilanthus is a valid one. It might be used as
a group; if so P. saxigenus should be placed in the group so
formed.
Palache and Merwin—Connellite and Chalcophyllite. 537
Art. LI.—On Connellite and Chalcophyllite from Bisbee,
Arizona; by C. Patacuse and H. E. Merwin.
Tue following note is based on a single specimen of connell-
ite sent to the Harvard Mineralogical Laboratory for identifi-
eation by Mr. W. B. Gohring. “This one piece, all that was
found, came from the Calumet and Arizona mine at Bisbee,
and was generously placed at our disposal by Mr. Gohring.
The specimen is a flat fragment about an inch square con-
sisting largely of connellite in groups of radiating needles of
characteristic dark blue color. On one side it is incrusted with
cuprite and dark green melanochalcite. On breaking it apart
a small cavity was exposed, in which were a few terminated
needles of connellite, several cubical crystals of cuprite, and
several dark green flat crystais of chalcophyllite, mistaken at
first for spangolite.
The needles of connellite are deeply striated lengthwise, but
could be adjusted accurately on the two-circle goniometer not-
withstanding, and gave fair readings for the terminal planes.
These seem to be confined to faces of the unit pyramid; both
first and second order prisms are apparently present. The
largest crystal measured was about 0°5"" in diameter; the
average needle was much more slender, however.
The aver age of nine values (on two crystals) for the angle
0001 A 1011 was 53°50’ corresponding to an axial ratio
@:¢e=1:1185. This value is much nearer to that of Story-
Maskelyne, @:¢0=1-156 than to the ratio deduced from Pen-
field’s measurement of the pyramid angle, a@:¢= 1339; it is
probably based on better measurements than either.
The needles of connellite show no cleavage. The specitic
gravity is 3°396, determined by suspension in barium-mereuric
iodide (Merwin).
Optical properties. —(Merwin). Uniaxial, positive. Refrac-
tive indices :w = 1°724;« = 1°746; determined under the micro-
scope by bringing mixtures of ‘monobromonaphthalene and
sulphur dissolved,in methylene iodide to match the indices of
refraction as nearly as could be done by observing the Becke
effect : the refraction of the liquids was then found by means
of the reflectometer. The color is a clear, deep, slightly
greenish blue even in microscopic fragments.
The birefringence was determined independently of the
refractive indices by the following method: Various-sized
minute prisms of the mineral placed hetween crossed nicols
under the microscope showed only three distinct colors, blue,
purple and green. In case blue appeared the interference
color was, of course, blue, and in case purple appeared the
588 Palache and Merwin—Connellite and Chalcophyllite. —
interference color was red. From either of these colors the
difference of retardation of the two refracted rays could be
closely estimated. But when green was the color assumed, the
interference color might have been either orange, yellow or
green. In this case the one-quarter undulation mica plate was
inserted so as to raise or lower the color a sutfticient amount to
produce either blue or purple. Then by making proper allow-
ance for the mica plate the mterference color was calculated.
By measuring the thickness of the prism the birefringence of
the mineral was calculated from the interference color and
found to be ‘021. This figure, the mean of seven observations,
is as likely to be correct as the one derived from the refraction
indices, -022.
Chemical composition—(Merwin). Material sufficient for
chemical analysis (0°73 gram) of ideal purity was easily
obtained by hand-picking. ‘The analysis is compared below
with the only other one we have, that of Penfield made on
‘O74 gram, and leads to a somewhat different formula. The
water was given off in three distinct fractions at about 235°,
260° and incipient redness. A little of the second fraction of
water was seen to come off before the heat was removed in
estimating the first fraction.
Connellite, Molecular Ratios Connellite,
Merwin (fsecessee's =~ Pentald
SOR ici en se 3-43 043 98 ail 4:00 061 tte
Ci a ae es 6:37 18 0 4:09) 4 WA 0G) aed
CHO di denny, 715-96 959 21-84 22 79-3 918 15
HO below 22008: Sipe coma ‘A
HO, 220°—260° __. 12°06 al nae
HO, 260° 300° 2:10 117-965 6. 20 16-8 988 15-3
EL cuore sO. 1:66) | 0024 sn ental \
101-83 101°8
Ibs QaSOlh e 1°42 1°67
Totals eke 10041 100-13
As shown by the molecular ratios, the composition of this
connellite may be expressed by the empirical formula
Cu,,Cl,SO,, + 20H,O. The corresponding formula for Pen-
field’s analysis is Cu,,(Cl-OH),SO,,+15H,0.
The distribution of the water might be accounted for by
supposing some such molecular grouping as this:
[CuSO,.3Cu(OH),.H,O].2[ CuCl,.Cu(OH),].14[Cu(OH), |.
The first part of this formula is identical with that of the
mineral langite, which loses one equivalent of water at a
moderate temperature. The fact that when first heated con-
nellite yields water alone indicates the presence of a copper
hydrate molecule easily decomposed by heat; thus the fifteen
Palache and Merwin—Oonnellite and Chalcophyllite. 539
equivalents of water first given off are accounted for in our
formula: cupreous chloride volatilizes at a higher temperature,
and finally chlorine and sulphur trioxide are expelled.
Penfield’s analysis of connellite from Cornwall may be repre-
sented by a molecular grouping of the same general form as
the above, but quite different in its proportions:
[CuSO,.3Cu(OH),.H,O].2/CuCl,.Cu(OH),.H,O].7/ Cu(OH), J.
Chaleophyllite was identified in the specimen by measure-
ment of crystals, and by qualitative chemical tests for arsenic,
copper and aluminum. Most of the crystals were irreoular
plates embedded in the connellite. The perfect basal cleavage
and rich green color were conspicuous features. A single
minute implanted crystal was obtained, which fare extremely
satisfactory readings for the forms ¢ (0001), « a(1014), ¢ (0112),
r (1011), and y (0221). Of these forms # is new, and y does
not appear in Dana’s list, although given by Goldschmidt
(Winkeltabellen). The measured angles differ considerably
from those derived from Des Cloizeaux’s element (crystals
from Cornwall), and a new ratio was therefore calculated, as
shown below:
Gps = 1.2 2°554 pi =a 102 Des Cloizeaux.
Gace —- F267 1 (Pa lel 30 Palache.
Calculated
Des Cloizeaux Palache Measured No. of faces
mmole Cons WO. = 2 2 5 26°10! DS —
COA se a eee —— 37 38 aay 3
eet sk Meee. 44 30 45 08 = —_
CONS Came a a0 Ol 57 02 56 59 3
(itor ol Piles in Restos 71-16 i202 A OD 3
CRY ae eS —- 80 48 fel Oil 2
The measured crystal is of rhombohedral habit with the unit
form dominant and very small base.
As this mineral was first mistaken for spangolite, it seems
worth while to note here the close similarity in physical char-
acters existing between the two. Both are soft, dark green,
hexagonal with perfect basal cleavage, and optically negative.
Furthermore, the chalcophyllite rhombohedrons have inclina-
tions to the base which are closely aches by pyramids occur-
ring on spangolite.
Unfortunately there was not enough of this material for
quantitative analysis, which would have been desirable in view
of the uncertainty as to the composition of chalcophyllite.
Considerable interest attaches to the occurrence of these
minerals at Bisbee, because of their association elsewhere with
540 RL. PP. D. Graham—Optical Properties of Hastingsite.
spangolite. It will be recalled that the type specimen of
spangolite came from an unknown locality in southern Arizona,
With it were minute blue prismatic crystals, not determined
by Penfield, but suggesting connellite. While spangolite has
not yet been found at Bisbee, it now seems highly probable
that the original specimen came from there, and that it may be
rediscovered if carefully sought for.
Mineralogical Laboratory, |
Harvard University, July, 1909.
Arr. LIT.—On the Optical Properties of Hastingsite from
Dungannon, Hastings County, Ontario; by R. RP. DW. -
GRAHAM. :
In a paper which appeared in this Journal for July, 1894,
the discovery of a large area of nepheline syenite in the town-
ship of Dungannon, in the Province of Ontario, was announced
and the geological relations and mineralogical characters of
the mass were briefly described. Further exploration showed
that the nepheline syenites in this part of Ontario had a very
wide distribution and the results of a detailed study of them
has just appeared.* In the township of Dungannon, about
two miles east of the village of Bancroft, the nepheline syenite
contains a remarkable hornblende associated with a titaniferous
andradite ; these minerals were analyzed by Dr. Harrington
‘and their chemical composition was discussed in a paper
which appeared in this Journal in March, 1896.¢ No thorough
examination of the optical properties of the remarkable horn-
blende, however, has hitherto been made, and the writer, at the
request of Dr: Adams, has studied the mineral with a view to
the determination of its optical characters.
The material employed was that obtained by Dr. Adwae at
the original locality above mentioned.
The hornblende is distributed throughout the rock in fairly
large amount as small black individuals or agoregates. with a
high luster, especially on the cleavages; but no fragments
having crystal faces were found on the specimen examined.
eCopt in very thin flakes, it is practically opaque.
*The Nepheline and Associated Alkali Syenites of Hastern Ontario, by
aaaee | Adams and Alfred E. Barlow; Trans. Royal Society of Canada,
+Onanew Alkali Hornblende and a ‘Hhsniokeeenom: Andradite from the
Nepheline Syenite of Dungannon, Hastings Co., Ontaric, by Frank D. Adams
and B. J. Harrington.
R. P. D. Graham—Optical Properties of Hastingsite. 541
Under the microscope in parallel light, thin sections appear
quite fresh and greenish in color, with a very strong
pleochroism. ‘Those rhomb-shaped sections, which are cut
more or less perpendicular to the prism, and show the two sets
of cleavage cracks intersecting at about 56°, are yeilowish
green for light vibrating along the shorter diagonai of the
rhomb, and deep bluish green, or nearly opaque if the section
is at all thick, for light vibrating parallel to the longer
diagonal. Prismatic sections are also ver y strongly pleochroie,
appearing deep bluish green to opaque when the light trav-
ersing them vibrates along the cleavage and pale yellowish
green for light vibrating perpendicular thereto. Between
crossed nicols the latter have various angles of extinction with
the cleavage cracks, the maximum value observed being about
30°.
Some fragments, however, while being distinctly pleochroic,
exhibit this. property in a ‘comparatively slight degree, and
these are further found to be almost isotropic between crossed
nicols. When examined in convergent light, a dark cross,
somewhat blurred and thickened at its center, is seen, and it
was this unusual feature which first drew special attention to
the mineral. The cross does not separate into very definite
hyperbolas on rotating the section, owing to its ill-defined
character, but that the mineral is not truly uniaxial is evident
from the pleochroism of these sections and also from the
unsymmetrical manner in which the brushes are colored.
In the paper referred to above, it was stated that the axial
angle is over 30° and possibly as much as 45°, the optic axes
lying in the plane of symmetry, with a strong dispersion in the
sense p > Uv.
The optical determination of the mineral in the ordinary
rock sections is a somewhat difficult matter, owing to the fact
that even the thinnest slices, when cut normal to the acute
bisectrix, have a very deep bluish green color, causing the
whole field to be dark, while the power of the objective under
which it can be examined is also necessarily limited in such
cases. In the present instance, small chips of the mineral
were crushed very finely under oil and examined under a 1/12”
oil immersion objective. The majority of the fragments
were minute cleavage flakes, with a high extinction angle, the
mean observed value being 22°, and they exhibit the strong
pleochroism noted above for prismatic sections. The bire-
fringence is low, compensation taking place when the quartz
wedge is inserted across the prism. The dark brush which
crosses the field on rotating the section (or the nicols) in con-
vergent light is broadly fringed with red on one side and blue
on the other, indicating a strong dispersion.
Am. Jour Sci1.—FourtH Series, VoL. XXVIII, No. 168.—Drcremeper, 1909.
36
542 PR. P. D. Graham—Optical Properties of Hastingsite.
But there are always a few fragments lying on a plane
which is approximately normal to the acute bisectrix and when
these are sufficiently thin they exhibit a fairly well-defined
optical figure. As had been previously noted, the central part
of the interference figure, even when in the diagonal position,
is not well illuminated, owing to the deep color and the weak
double refraction of the mineral. The quasi-uniaxial figure is
colored red in one pair of opposite quadrants, transverse “to the
cleavage cracks, and bluish green in the other, and it is usually
difficult to decide as to which of these directions is the line
joining the optic axes. [ the axial plane lies in the plane of
symmetry, as is usual in hornblende, then the angle for red is
greater than that for blue, orp > v. But when exceedingly
thin and less highly colored chips are examined, it.is found
that the hyperbolas open out across and not along the plane of ©
symmetry. They are colored red on their coneave side, and
although the brushes are thick and frayed, a certain amount of
bluish green light gets through in the narrow space which
separates them, and the same color tints the rest of the figure.
It was at first thought that this effect might be only an illu-
sion and due to the fact that more light is transmitted near the
red portions of the figure than elsewhere, thus causing an
apparent opening of the hyperbolas in this direction. . But the
phenomenon was observed in many cases so clearly as to admit
of no doubt in the writer’s mind that in hastingsite the axial
plane, for green light at least, hes at right angles to the plane
of symmetry of the mineral ; the axial angle for red hght is
less, and there may even be a crossing of the optic axial plane
for these colors, since the interference figure observed in yel-
low light appr aches more nearly to ‘the uniaxial CLrOss,
although it is very ill-defined owing to the poor illumination of
te teldas ine birefringence i is weak and negative. Although
the pleochroism of sections cut in this direction is compara-
tively slight, it is in the same sense as that noted above for
those par rallel to the prism.
Considered with reference to the crystallographic axes, the
pleochroism is like that usually met with in amphiboles; but
since in the case of hastingsite the plane of the optic axes lies
across the plane of symmetry instead of along it, we have
b>c>a, 6 and c being nearly equal.
It is impossible to make any accurate measurement of the
optic axial angle, but it is evidently quite small. It was
thought that it might be useful to make a rough estimate of
its value by comparison with some other mineral of small
angle, and biotite was selected for this purpose. A cleavage
flake, in which the hyperbolas separated to about the same
extent, so far as could be judged by the eye, as in the case of
R. P. D. Graham— Optical Properties of Hastingsite. 5438
hastingsite, when examined under similar conditions, was
found to have an axial angle, 2V = 17° 12’; and allowing for
the difference in refractive index between the two minerals,
this would give for hastingsite, 2V=16°. From. the nature
of the method employed in arriving at this value, it can at the
best be considered only as an extremely rough approximation ;
but it serves to indicate the probable order of the axial angle,
which is much smaller than at first suggested.
The mean refractive index was determined by Schroeder
van der Kolk’s method, using thin cleavage fragments placed
in the position of least absorption, i. e., for hght vibrating
across the prism. The lhquids employed were methylene
iodide and naphthalene monobromide, which mix to form a
clear solution. The refractive index of the resulting mixture,
after adjusting as nearly as possible to that of the mineral,
was determined in the usual manner by means of a hand refrac-
tometer. The mean of several determinations gave 1°69 as the
index of refraction of the mineral for light traversing it in this
direction.
Geological Department, McGill University, Montreal.
544 Gooch and Read—Determination of Chlorine.
Arr. LIT.—TZhe Electrolytic Determination of Chlorine in
Hydrochloric Acid with the Use of the Silver Anode ; by
F. A. Goocu and H. L. Reap.
[Contributions from the Kent Chemical Laboratory of Yale Uniy.—ceyv. ]
In Vortmann’s work* upon the electrolytic determination of
the halogens with the use of a silver anode, the determination
of iodine in iodides was demonstrated experimentally ; ; and the
statement was made, with the promise of future demonstra-
tion, that chlorides ‘and bromides are susceptible of similar
treatment. It was shown that when a suitable electric current
is passed through a solution containing a moderate amount of
potassium iodide and a proper amount of sodium hydroxide,
iodine may be fixed upon the silver anode while potassium
hydroxide is formed at the platinum cathode. It was found
that the addition of an alkali tartrate (3 erm. of Seignette salts)
aided the fixation of the iodine as silver iodide upon 1 the anode,
but excepting the cases in which the amount of iodide handled
was very small, good results were also obtained without the
use of the tartrate. In this work,a disc of silver 5™ in
diameter was used as the anode and a similar dise of
platinum, or a platinum dish, served as the cathode ; the total
volume of the solution was 100°™ to 150°™*, containing 6%™* to
10° of a 10 per cent solution of sodium hydroxide; and the
current, less than ‘07 ampere under a potential not exceeding
2 volts, was allowed to act for several hours. ‘The end of the
electrolysis was determined either by testing a few drops of
the solution for iodine or by putting in fresh anodes until no
more silver iodide was formed upon the anode surface. To
determine the increase in weight of the anode due to fixation
of iodine, the anode was removed from the liquid, washed
with water and with alcohol, dried over a Bunsen flame, and
finally heated to dull redness or to the fusing point ot silver
iodide for the purpose of removing oxygen ‘also fixed upon
the anode. Tt was noted that small amounts of silver (00010
germ. to 0°0015 grm.) were dissolved from the pure silver anode
and deposited to some extent upon the platinum cathode ; but
to completely deposit upon the cathode the dissolved silver it
is recommended to introduce a platinum anode after removing
the silver anode and to pass the current for an hour. The
sum of the increase in weights of both electrodes is the meas-
ure of the iodine fixed.
Vortmann thus emphasized strongly two points: viz., that
the silver anode should be heated to a temperature sufficient
to break away oxygen (held according to Vortmann in the
* Monatshefte f. Chemie, 15, 280 (1894) ; 16, 674 (1895).
Gooch and Read—Determination of Chlorine. 545
form of silver dioxide), and that account must be taken of
silver dissolved from the anode. These are points which
appear to have escaped the consideration of subsequent
workers.
Speketer,* in the electrolytic separation of chlorine, bromine,
and iodine under graded potential of current, dried the silver
anode at 120°.
Smitht deposited the chlorine of the chlorides of sodium,
barium and strontium upon an anode of silver gauze, the
cathode being either platinum or mercury used as described
by Myers.{ Upon passing the current the silver began to
darken almost immediately from the lower edge upward, and
when no further progress in the darkening was observed, it
was assumed that the operation was at an end. The gauze was
rinsed with water, alcohol, and ether, and was weighed after
drying a short time. The alkali in solution was determined
by titration with standard acid.
Withrow§ determined similarly the iodine of potassium
iodide and the chlorine of potassium chloride with the use of
a spiral platinum cathode rotating at 300 to 5V0 revolutions
per minute and a silver dish used as the anode. The deposit
was dried in an air bath for weighing.
Hildebrand| made use of an anode of silver gauze, either
stationary or rotary, with either a simple mercury cathode or
a mercury cathode arranged so that an amalgam of the liberated
metal might be formed in aninner compartment and decom posed
largely in an outer annular compartment. The gradual fall-
ing of the current to a minimum (0:005 to 0:02 amperes),
determined by the formation of a small amount of alkali in
the solution, indicated the advance of the process to completion.
Hildebrand noted: that after all the salt had been decomposed
the weight of the silver anode might be indefinitely increased
by the formation of silver oxide upon it, and, to avoid con-
tinuing the electrolysis after complete decomposition of the
salt, adopted the plan of diluting the liquid when the current
had apparently reached its minimum and stopping the current
as soon as the fresh anode surface thus brought into action
showed the formation of brown silver oxide. The gauze was
removed, immersed in alcohol and then in ether, dried,4/ and
weighed. To secure the double advantage of making the
anode deposits perfectly adherent and stirring the amalgam to
secure complete decomposition in the outer compartment,
rotation of the anode was tried, and the statement is made
* Zeitschr. f. Electroehem., 4.
+ Jour. Amer. Chem. Soc., xxv, 890 (1903). tIbid., xxvi, 1124.
§ Ibid., xxviii, 1350 (1906). | Ibid., xxix, 447 (1907).
Patio Electro Analysis (1907), p. 305. ‘‘ Dry the gauze over a steam
Tadiator.
546 Gooch and Read—Determination of Chlorine.
that when the rotating anode was used in the double cell
nothing but pure water remained in the inner compartment
after the salt under examination had been decomposed ; that
the falling of the current to 0-01 ampere or less indicated
the end of the process; and that no harm could be done by
running longer, as further increase im the weight of the
anode was not possible. The results obtained by weighing
the anode were concordant with one another, close to the
theory, and in agreement with the figures obtained by titration
of the alkali formed in the liquid.
McCutcheon,* Lukens and Smith,t and Lukens and
McCutcheon,t have studied still further the behavior of
various chlorides, and other salts, in electrolysis with the use of
the rotary silver anode and the mercury cathode.
Throughout all the later elaborate experimentation no
reference is made to the points emphasized by Vortmann as
necessary in the electrolytic determination of iodine, viz., the
ignition of the silver anode to break away fixed oxygen and
the determination of silver dissolved or carried to the cathode.
From aconsideration of the apparently very exact results
obtained in the treatment of various chlorides it would seem
that nothing could be simpler than the accurate determination
of chlorine in hydrochloric acid by similar means. That such
is not the case, however, will be seen from the following
account of experimentation upon the electrolytic determination
of chlorine in hydrochloric acid with the use of the silver
anode. In a preliminary experiment a large silver crucible
was used as the anode with a smaller platinum cathode, and
a current of 1°5 to 0°09 amperes under a potential of 3°5 to 4
volts passed for an hour through a solution containing origi-
nally 0°2184 orm. of hydrogen chloride. It was found in this
experiment that the combined weights of anode, cathode, and
suspended silver compound collected on asbestos failed by
several milligrams to make up the weight of chlorine contained
in the hydrogen chloride; and testing of the residue left after
evaporation of the clear filtrate showed distinctly the presence
of a chlorate.§
In another experiment, similar excepting that the voltage of
the current was raised as the operation progressed, a current
of 0°5 to 0°24 ampere under a potential of 4 to 80 volts was
passed for thirty minutes through a solution containing at the
outset 0°2184 orm. of hydrogen chloride. The combined
* Jour. Amer. Chem. Soc., xxix, 1445. + Ibid., xxix, 1400.
t Ibid., xxix, 1460.
§ The test for a chlorate was made by treating a portion of the residue
with a saturated solution of manganous chloride in hydrochloric acid (Gooch
and Gruener, this Journal, xliv, 118, 1892).
Gooch and Read— Determination of Chlorine. 547
weights of the ignited anode, cathode, and suspended silver com-
pound here also fell short of the weights of chlorine present
by 0°0039 grm. In this case the suspended precipitate was
brownish, and the clear filtrate deposited upon standing for
forty-eight hours a precipitate which, when filtered off and
treated with hydrochloric acid, and dried, weighed 0:0029 grm.
On standing for a week the filtrate threw down another shght
deposit. Silver oxide was plainly found at the anode, and the
behavior of the clear filtrate is suggestive of the formation of
silver hypochlorite and its subsequent transformation to insolu-
ble silver chloride and silver chlorate.
In a third experiment, essentially similar to the first except-
ing the use of a platinum cathode, the formation of a deposit
of silver upon the cathode was distinetly visible. It is plain,
therefore, that the solution of silver from the anode, the
deposition of the silver upon the cathode, the production of
oxygen acids of chlorine (hypochlorous acid and chlorie acid)
and possibly their silver salts, are phenomena likely to occur
in the electrolysis of hydrochloric acid with the use of the
silver anode.
In subsequent experiments the rotating anode of the form
used by Hildebrand,* consisting of two circular disks of
platinum gauze of 300 meshes to the square centimeter, 5
centimeters in diameter and mounted 5 millimeters apart and
parallel to one another upon a perpendicular wire of platinum
used as the axis of revolution, was substituted for the stationary
anode. This apparatus was plated with silver by rotating it as
the cathode in a solution of potassium silver cyanide. After
plating, it was prepared for use by careful washing, drying,
and ignition to incipient redness in the tip of a Bunsen flame.
A 200°* platinum dish was used as the cathode. The pure
hydrochloric acid employed was made up of approximately
N/10 strength. Itwas standardized by precipitating with silver
nitrate in the hot solution and weighing the silver chloride
filtered after standing over night “and. chillmg. Parallel
determinations showed 0:4247 erm. and 0-42.48 orm. of
chlorine in 100%". The residue left by evaporation of 25°™ of
the solution was found in parallel experiments, one at the
beginning and the other at the end of work, to be 0-0001
grm. and 0°0003 grm.
In each experiment a portion of the standard acid, usually
25°, was drawn from a burette into the 200° platinum dish
which served as the cathode. The dish with contents was
adjusted, the anode set in the rotating apparatus, and the
solution so diluted that the anode dipped well under the liquid
while distant from the cathode by about 1. The anode was
* Jour. Amer. Chem. Soc., xxix, 450, 1907.
548 Gooch and Read— Determination of Chlorine.
rotated at about 300 revolutions to the minute, and the current
turned on. At the end of the time recorded the anode was
removed from the liquid, washed carefully with aleohol and
then with ether, dried carefully by slow agitation well above’
the Bunsen flame, and weighed ; thereafter it was ignited to
incipient redness at the top of the Bunsen flame and weighed
again, this operation being repeated to insure a constant weight.
In the ignition, the dark color of the anode, taken on in elec-
trolysis and retained throughout the drying process, largely
disappeared. It was determined experimentally that the
anode and deposit dried in the manner described incurred no
further loss of weight when heated in the air bath at 105°-110°;
and a single ionition served to bring the anode and deposit to
the second constant weight.
The hquid remaining after electrolysis was tested with
litmus paper and then subjected to the further tests indicated
in the accounts of individual experiments. The cathode was
examined for deposited silver, and in some cases this was
dissolved off the platinum in nitric acid, precipitated as silver
chloride, and weighed. The details and results of the experi-
ments are summarized in Table I.
In the experiments of Series A of the table, the apparent
error in terms of chlorine, as determined from the weight of
the carefully dried anode, varied from —0:0019 grm. to
+0:0022 grm.; but it is to be noted that the dried anodes lost
upon ignition amounts varying from 0-0030 grm. to 0:0070
grm., these losses being presumably due to the expulsion of
oxygen fixed in the electrolysis. Obviously, the amount of
chlorine fixed cannot be calculated from the weights of the
dried anodes. If the weights of the ignited anodes ‘be taken as
the basis for the calculation of fixed chlorine, the errors of the
chlorine determinations vary from —0:0026 grm. to —0:0072
orm,
aia every case but one (5), the solution was neutral to htmus
paper at the end of the period of electrolysis, which shows
that in these determinations no hydrochloric acid remained as
such. In each of two cases silver was found upon the
platinum cathode to the amounts of 00011 grm. and 0°0015
grm. respectively, these amounts being determined by dissolv-
ing the metallic deposit in nitric acid, and weighing the
silver chloride precipitated by hydrochloric acid from the
solutions thus obtained. Plainly part of the apparent error in
the fixation of chlorine is due in these cases to the transfer of
silver from the anode to the cathode. Of the liquids tested,
all but one became opalescent upon the addition of silver
nitrate, as might be expected if hypochlorous acid or a hypo-
chlorite, neither of which would turn blue litmus paper red,
of Chlorine. 549
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Gg
O&
GT
OF
“ULUL
ouLT,
2901-0 (8)
Z90T-0 (4)
3901-0 (9)
S90T-0 (¢)
Z90L-0 (#)
2901-0 (gs)
2901-0 (2)
6901-0 (1)
“ULLS
IOH
UL UEyRy
auLLO[yO
‘NOILNIOG HAUINVAY) V NI daLVId-HHATIG AMONY WHHL HLIM GIOY OLMOTHOOUGAPFT #O SISA TOMLOW IY —']T WIV 7,
550 Gooch and Read—Determination of Chlorine.
were contained in the solution. In one experiment (6) the
solution, neutral to litmus, became spontaneously opalescent
after standing forty-eight hours, as might very well be the
case if the solution contained a trace of silver hypochlorite at
the end of the electrolysis. These phenomena show that in
the electrolytic analysis of hydrochloric acid with the silver-
plated anode the process does not consist simply of the libera-
tion of hydrogen at the cathode and the fixation of chlorine at
the anode, but that these effects may be supplemented to a
greater or less extent, according to the conditions, by the
fixation of oxygen as well as chlorine, the production of
oxygen compounds of chlorine, and the dissolving of silver
from the anode with its more or less complete transfer to the
cathode. Of silver in solution a trace was sometimes found by
hydrogen sulphide but not enough to give a distinct test with
hydrochloric acid, though in experiment (6) a trace of silver
chloride was apparently thrown out spontaneously on standing.
In expermments (4) and (6) tests of the liquid with silver
nitrate were omitted and the residues left on evaporation and
heating were found to weigh 0:0029 and 0:0035 grm. respec-
tively. Each residue was soluble in water and, after ignition,
gave a test for chlorine with silver nitrate. Each contained
no appreciable amount of silver, but did contain potassium ;
and, inasmuch as the acid taken left upon evaporation only an
inconsiderable residue, the inference seemed plain that at least
the greater part of the solid material must have been derived
from salt included in the plating of the anode. before pro-
ceeding further, therefore, this point was decided by carefully
washing as usual a freshly plated anode, suspending it for some
minutes in a beaker of water kept boiling, and then testing
the water with silver nitrate, the production of cloudiness
being taken as an indication of the presence of a soluble
cyanide.
In Series B of the table are the results obtained in-two
experiments with the silver-plated anode carefully boiled out
and gently ignited previous to its use in the electrolytic
process. In experiment (8) mercury in a glass beaker and con-
nected with the battery by a platinum wire sealed into glass to
prevent contact with the liquid served as the cathode. In
each of these experiments the neutrality of the residual liquids
proved the absence of hydrochloric acid. In (7) a trace of
silver was found upon the cathode, and the liquid became
faintly cloudy toward the end of the electrolysis and left upon
evaporation a residue of 0:0024, of which 0:0011 was insoluble in
water and apparently silver chloride. In (8) a small portion
of the liquid gave a precipitate with silver nitrate and the
remainder left a residue of 0°0020 grm. These results confirm
Gooch and Read—Determination of Chlorine. 551
those of Series A and show errors of the same sort, though
the soluble residue was considerably less. Apparently material
included in the silver plating of the anode was not wholly
extracted by the process of washing and boiling.
The next experiments were made with the rotating gauze
anode plated with silver from a solution of silver oxalate in
ammonium hydroxide to avoid all possible contamination of
the silver deposit by nonvolatile material. The course of the
electrolysis was similar to that of the experiments previously
described, nearly to the finish; but, near the end, when neu-
trality to litmus indicated the exhaustion of hydrochloric acid,
the solution suddenly became opalescent and soon afterward the
current practically ceased to flow. Upon standing, the liquid,
which at the end of the electrolysis had slowly bleached blue
litmus paper without reddening it, developed distinct acidity,
and when tested in separate portions gave further opalescence
with silver nitrate and set free iodine from potassium iodide.
All these phenomena point to the formation of hypochlorous
acid in the process of electrolysis and its attack upon the
anode to form silver hypochlorite and derived silver salts.
It appears further, that in the absence of alkali salt, soluble silver
hypochlorite, apparently formed chietly when the hydrochioric
acid approaches the point of exhaustion, is thrown into solu-
tion, to be partially decomposed with production of opalescent
silver chloride. In Table II are given the details of experi-
ments made with the silver anode plated in the oxalate solution.
In the first experiment the electrolysis was continued until the
current practically ceased to pass. In the other experiments
the operation was ended when the diffusion of the opalescent
silver chloride indicated that the silver anode was being attacked,
dissolved, and partially reprecipitated in the liquid. In all the
liquid was neutral at the end of the electrolysis.
The results of these experiments, in which no alkali salt
derived from the plated anode could be present, confirm those
of the preceding series in respect to the fixing of oxygen as
well as chlorine upon the anode, the removal of silver from
anode to cathode, and the formation of hypochlorous acid.
It is plain, therefore, that the electrolytic determination of
the chlorine of hydrochloric acid with the use of the silver
anode is by no means an exact process. Even when precau-
tions are taken to plate the anode with a silver solution con-.
taining salts which, if included in the deposit, will leave
nothing but silver, and to ignite the anode with the electrolytic
deposit to the point of decomposition of attached silver oxide,
the results are very irregular and always low.
The Electrolysis of Hydrochloric Acid with a Silver Anode plated in
552 Gooch and Read—Determination of Chlorine.
Tas.e II.
the Oxalate Solution.
la
2b
3C¢
Ad
dé
6f
| Increase Apparent | Apparent
: of anode Loss of error in error in
Chlorine | dried in | Increase dried chlorlne chlorine
taken air bath of anode |when anode when anode.
in ©. Current | at anode on was was
HICEy eh 105°-110°| ignited ignition dried ignited
erm. jag amp. volt | grm. grm. grm. germ, grm.
0°0533)/ 25} 0°5-0°'01
0°0533) 30} 0°5—-0°01
0°0533) 25) 0°4-0°08 3
79| 0°0533)| 25| 0°4—0°02 3
0°0533) 25| 0°5-0'00 2-4) 0°0513) 0:0502 0:0011) —0:0020; —0:0031
0:0533) 30/0°45-0°01 2-4 0:0529| 0°0520; 0:0009| —0°0004| —0°0018
3-4 0°0513) 0°0501} 0:0012) —0:0020| —0°0032
38-4) 0°0523/ 0°0517 0:0006) —0:0010| —0°0016
0°0533) 25) 0°5-0°01 3°8—4| 0°0517| 0°0499 0:0018) —0:0016) —0°0034
°8—4
‘8-4
a.—The solution became suddenly opalescent and soon thereafter the cur-
rent practically ceased, the liquid being neutral to litmus paper.
Silver chloride (0:0017 grm.) was recovered from the liquid, and silver
was found upon the cathode.
b.—The electrolysis was interrupted ot the first appearance of opalescence,
the liquid being neutral. No silver was found. in soluticn and none
upon the cathode. Iodine, indicated by starch, was liberated when
potassium iodide was added to a portion of the solution.
c.—At the end of the electrolysis the liquid was slightly opalescent and
neutral to litmus. Upon the addition of potassium iodide to a portion
of it a trace of iodine was set free. In another portion, silver nitrate
was without immediate effect. A trace of silver was found upon the
cathode.
d.—At the end of the electrolysis the liquid was slightly opalescent. It
was neutral to litmus, but slowly bleached the color. Upon standing
it developed acidity. From potassium iodide it liberated iodine equiva-
lent to 0:0010 grim. of chlorine, as was determined by sodium thiosul-
phate. A trace of silver was found upon the cathode.
e.—At the end of the electrolysis the liquid was slightly opalescent. It
was neutral to litmus but developed acidity in the course of a half-hour.
From potassium iodine a portion set free iodine. In the remainder
silver nitrate gave, after standing two days, an amount of silver
chloride equivalent to 0°0016 grm. of chlorine. Silver was found upon
the cathode.
jf.—At the end of the electrolysis, the liquid was slightly opalescent. It
was neutral to litmus, but developed acidity on standing a half-hour.
From potassium iodide a small portion set free iodine. From the
remainder silver nitrate precipitated silver chloride, which, when filtered
off after five days, was found to be equivalent to 0:0035 grm. of
chlorine. <A trace of silver was found on the cathode.
g.—At the end of the electrolysis, the liquid was slightly opalescent. It
was neutral to litmus, but developed acidity in a half-hour. A small
portion of it set free iodine from potassium iodide. Silver nitrate pro-
duced in the remainder, after four days, a precipitate of silver chloride
equivalent to 0:0036 grm. of chlorine. No silver was found upon the
cathode.
0°0502) 0°0493 0:0009| —0:00381) —9°0040
0:0506| 0:0493 0:0013} —0:0027| —0:0040
Chemistry and Physics. 553
SOCLEN TIP ICUOINTRLELGENCE-.
I. CHEMISTRY AND PHYSICS.
1. Boiling-points of Metals.—Our data in regard to the boiling-
points of most of the common metals have been very uncertain
and discordant, but H. C. GrreENwoop has recently made an
extended investigation of this subject, and has succeeded in
determining a number of these constants with a fair degree of
approximation. He employed a slender graphite crucible placed
in a slightly larger vertical carbon tube which was heated by
electrical resistance. The temperature was measured by observa-
tion of the walls of the crucible through a horizontal tube con-
nected with the carbon tube, by means of a Wanner optical
pyrometer. The surface of the metal was observed through a
window at the top of the apparatus, and its agitation indicated
the boiling-point. A current of hydrogen was passed in at the
side tube, as a protection to the crucible. It was found that the
boiling-points were lower in the presence of a current of hydrogen
than in the case where nitrogen was used, apparently on account
of the fact that hydrogen easily penetrated the walls of the hot
crucible and carried off or diluted the column of heavy vapor
above the metal. In the cases of the metals which form carbides,
the interior of the crucible was coated with magnesia in such a
manner that practically no carbide was produced. When this pre-
caution was not taken, boiling-points several hundred -degrees too
high were obtained in some cases. The following table gives the
results as the approximate boiling-points of eleven metals:
Ainmimnium ._._ 1800° ©. bead ee ee 145 (OP
Antimony ----- 1440 Magnesium .--- 1120
Bismuth... 1420 Manganese. .--- 1900
Chromium .... 2200 SilVeta ose = ORS
Copper 2... 2310 TI es ee eee 2210
_ oi eee 2450
— Chem. News, c, 39, 49. : FOGLE
2. Sodium Alum.—This alum, NaAl(SO,)},.12H,O, was made by
several of the earlier investigators, but its existence has been
questioned several times. For instance, Ostwald in his ‘‘Principles
of Inorganic Chemistry” states that sodium and lithium do not
form alums. W. R. Smira has now shown conclusively that the
sodium alum may be easily prepared in well-developed crystals
of the usual octahedral form, but he has shown also that it does
not exist at temperatures much above 30° C. Above this tempera-
ture the separate salts crystallize side by side, and when the alum
in contact with its saturated mother liquor is heated to the higher
temperature it is decomposed into an opaque, finely divided mass.
Jour. Amer. Chem. Soc., xxxi, 245. H. L. W.
554 Scientific Intelligence.
3. The Elements of Metallography; by Dr. RupotFr Rurer.
Translated by C. H. Marnewson. 8vo, pp. 342. New York,
1909 (John Wiley & Sons).—Nearly the whole of this book is
devoted to a very clear and full explanation of the recently
developed methods for studying alloys. ‘The theory of the fusion
diagrams and the microscopic structure of these substances is
discussed in an admirably simple and thorough manner. <A com-
paratively short second part of the book deals with practical
thermal and structural investigations. The translator has shown
excellent skill in putting the work into English. The subject is
of great importance both from practical and scientific points of
view, and this book will doubtless afford much pleasure and profit
to chemists and physicists, even though they may not be directly
interested in the subject of alloys. H. L. W.
4, Outlines of Chemistry with Practical Work ; by H. J. H.
FENTON. 8vo, pp. 364. Cambridge, England, 1909, at the Uni-
versity Press (New York, G. P. Putnam’s Sons).—This book
has been prepared for use in connection with the author’s course
of instruction in general and physical chemistry at Cambridge
University. It gives a somewhat condensed, but advanced,
treatment of theoretical chemistry, with practical experiments
for the student, usually at the end of each discussion of a lecture
topic. It appears that the student is expected here to learn the
theory and then, if possible, to study the facts which prove it.
The book is interesting and it should prove useful to American
teachers. The work does not cover the whole domain of chemi-
cal theory, but it is to be followed by a second volume.
A, iy Wie
5. An Elementary Treatise on Qualitative Chemical Analysis,
by J. F. Seruers. 12mo, pp. 176. Boston (Ginn & Company).
A Manual of Qualitative Chemical Analysis ; by J. F. Me-
GREGORY. 8vo, pp. 185. Boston (Ginn & Company).
These two text-books on qualitative analysis have just appeared
in the form of revised editions, which is an indication that they
have been extensively used. Both books follow practically the
conventional course of analysis, and differ chiefly in the manner
in which it is presented, and in the theorotical matter which is
introduced. A considerable variety of text-books in qualitative
analysis is required to meet the demands of teachers with courses
of different character and length. H. L. W.
6. The Periodic Law; by A. EH. Garrutt. 12mo, pp. 294.
New York, 1909 (D. Appleton & Company).—This book, which
is one of ‘‘ The International Scientific Series,” gives a very full
historical and theoretical discussion of the periodic classification
of the elements. The subject is ably presented, and the book is
supplied with many useful tables and diagrams. The subject is
brought up to the most recent times, including, for instance, a
discussion of Sir J. J. Thomson’s views in regard to atomic
structure, H. Le We
Chemistry and Physics. 555
7. A Text- Book of Physical Chemistry, Theory and Practice,
by Artuur W. Ewe... 8vo, pp. 370. Philadelphia, 1909 (P.
Blakiston’s Son & Co.).—The author states that the book is
intended to serve as a laboratory manual, as a text-book to accom-
pany recitations or lectures and as areference book. Much space
is devoted to directions for a course of laboratory experiments,
including the ordinary physico-chemical measurements and many
which would not ordinarily be given in a students’ course. These
directions appear to be very good. The theoretical and descrip-
tive part of the book is somewhat shorter and less complete than
is perhaps desirable. The author assumes that the student has a
knowledge of calculus. H. W. F.
8. A TLext-Book of Physiological Chemistry ; by Joun H.
Lone. Second edition, revised. 396 pp., with 42 illustrations.
Philadelphia, 1909 (P. Blakiston’s Son & Co.).—The second edi-
tion of Professor Long’s book represents a thorough ‘revision and
extension of the earlier one. The book is intended primarily for
use with laboratory classes, and is unusually well adapted to its
purpose. ‘The directions for the practical work are carefully pre-
sented, and serve to illustrate the more detailed discussion of the
remainder of the text. This plan has, in the reviewer’s opinion,
distinct advantages over the arrangement of isolated directions
found in the so-called manuals of chemistry. The physiological
bearings are never allowed to vanish into the background ; so
that the functions of living things are continually being empha-
sized from the chemical point of view. The book is particularly
adapted to the needs of medical students. i By Me
9. Positive Rays.—W. Wien continues his work of 1908 on
this subject and concludes his investigation as follows :
(1) The positive rays of hydrogen at high vacua are less
strongly influenced by magnetic fields than at low vacua.
(2) The rays which are weakened in a magnetic field are also
weakened in respect to heat properties and light emission by a
second magnetic field to approximately the same degree as those
rays which have not been affected by the first magnetic field.
' (3) The light emission is under otherwise equal conditions
much jess in high vacua than in low, and this is especially true of
hydrogen as well as air.
(4) The magnetic influence does not depend to a large degree
upon the potential difference exciting the tube.
(5) The canal rays of quicksilver do not convey a traceable
positive discharge, and no deflection can be observed in strong
magnetic fields by direct observation of the light emission.
The paper concludes with reflections upon the possibility of
combination and recombination of ions and electrons, and on the
possibility of light being emitted by positive ions in a neutral
condition.—Ann. der Physik, No. 12, 1909, pp. 349-368. 5. 7.
10. The apparent Fusion of Carbon in the Singing Arc and
in Sparks.—M. La Rosa gives a résumé of the work of Despretz
and Moissan on the production of artificial diamonds, and con-
556 Scientific Intelligence.
cluded to try the effect of a high tension spark on carbon dust
which is suitably placed in a cavity of one of the electrodes. A
current of 300 volts was employed: a side circuit included a con-
denser of 60 microfarad capacity with very small resistance and
self induction. It was found that the temperature of the singing
are under the condition in which it gives the spark spectrum is
much higher than that of the ordinary electric arc and the elec-
tric oven. The dust after the operation was carefully washed
and treated in various solvents; finally crystalline forms were
obtained of great hardness. The paper contains photographs of
these forms, which in the main were made up of two tetrahedrons
with curved surfaces. The author suspects that he has obtained
diamonds, and hopes to determine this question by further investi-
gation.— Ann. der Physik, No. 12, 1909, 369-380. Teej We
11. Determination of «/m.—Kurt Worz collects the various
determinations of this ratio and uses Bucherer’s method for a new
determination. He obtains «/m = 1:7674 x10’, while Bucherer
obtained ¢«/m = 1°763 x 10’.—Ann. der Physik, No. 12, 1909,
pp. 273-288. Jas
12. Spectroscopie Astronomique ; by P. Sauer. Pp. viii, 431,
with 44 figures and 1 plate. Paris, 1909 (Octave Doin et Fils).—
Under the direction of Dr. Toulouse the publication of a scien-
tific encyclopedia comprising twenty-nine volumes is projected.
As yet only two volumes have appeared, one of which has the
author and title indicated above. The subject of astronomical
spectroscopy is here presented from all points of view and in as
interesting a manner as is consistent with the relatively small
size (12°) of the pages. Although the text is somewhat synoptic
nevertheless it is fully up to date and contains references to the
latest discoveries as published in the scientific journals. At the
end of each chapter a bibliographical list of the most important
works relating to the topics discussed in the respective chapter is
given. The book concludes with an alphabetical index of authors
and of subjects together with a systematic table of contents.
Unfortunately most of the figures of spectra are somewhat
blurred and indistinct. However, on the whole, the volume
affords excellent reading matter introductory to a more detailed
study of astronomical spectroscopy. HLS aie
13. A Text-Book of Physics, Second Edition ; edited by A.
W. Durr. Pp. xi, 698, with 525 figures and’ 245 problems.
Philadelphia, 1909 (P. Blakiston’s Son & Co.).—The revised edi-
tion of this work (see vol. xxvii, page 85) differs from the first in.
the following respects. The chapter on wave motion, which was
formerly composed by W. Hallock, has been entirely rewritten
by E. P. Lewis. Many of the articles have been changed from
large to small type and vice versa. As a result the large print
portions of the book now constitute a well-balanced briefer
course. A number of the poorer figures have been replaced by
much better diagrams. Certain articles now conclude with illus-
trative tables of physical constants. At the end of each general
Geology. 557
subdivision of physics a list of well-selected reference books is
given. Also brief comments on the characteristics of these books
are made. Finally, the problems at the end of each complete
chapter have been classified with heavy type, marginal titles and
numerical answers are appended. On the whole, the book has
been greatly improved by the process of revision so that it is
now a thoroughly reliable text. H. 8. U.
14. General Physics: Mechanics and Heat; by J. A. CULLER.
Pp. ix, 311, with 225 figures. Philadelphia, 1909 (J. B. Lip-
pincott Co.).—This book is designed for the use of college stu-
dents who possess a working knowledge of plane trigonometry.
Proofs of various formule which involve the integral calculus
are given in the appendix. This portion of the book also con-
tains tables of physical constants, of natural trigonometric func-
tions, and of common logarithms. In the prefatory note, the
author says: ‘The aim of the writer has constantly been to say
the words that would help the student to understand the subject.”
In this endeavor as well as in the matter of accuracy of state-
ment he has often failed. ‘lwo typical quotations will suffice to
justify this adverse criticism.
On page 69 the following statements are made. ‘“ The centre
of gravity and centre of mass coincide, but their definitions are
different.” “The centre of mass is a point whose distance from
the three planes of reference is eyual to the mean distance of the
particles, supposed equal, from the same planes.”
On page 39 Newton’s laws of motion are stated in the follow-
ing new and incorrect forms.
“(1) Every body of matter persists in its state of rest or
motion.
“ (2) The effect of an impulse in changing the momentum of a
mass of matter is independent of other impulses which may be
applied at the same time and of the momentum which the mass
may already have.
(3) The application of a force is always accompanied by an
equal resistance in the opposite direction, and the energy
expended by any body acting as agent is equal to the energy
received by another body which resists the agent.” H. 8. U.
Il. Gerotoey.
1. Publications of the United States Geological Survey,
GrEoRGE Oris Smiru, Director.—Recent publications of the U.S.
Geological Survey are noted in the following list (continued
from p. 80):
Topocrapuic AtLas.—Thirty-eight sheets.
Foxrios —No. 166. El Paso Folio, Texas. Description of the
El Paso District ; by G. B. Ricnarpson. Pp. 11; 2 maps, 15
figures.
No. 168. Jamestown-Tower Folio, North Dakota. James-
town, Eckelson, and Tower Quadrangles. Description of James-
Am. Jour. ScI.—FourtH Series, Vout. XXVIII, No. 168.—DrcremsBer, 1909.
37
558 Scventifie Intelligence.
town-Tower District; by Danie E. Wittarp. “Pp. 10; 9 maps,
6 figures.
PROFESSIONAL Paprers.—No. 64. The Yakutat Bay Region,
Alaska. Physiography and Glacial Geology ; by Ratpu S. Tarr.
Areal Geology by Rarren 8. Tarr and Bert S. Burter. Pp.
183; 37 plates, 10 figures.
No. 66. The Geology and Ore Deposits of Goldfield, Nevada;
by FreprErick Lest1z Ransome, assisted in the field by W. H.
Emmons and G. H. Garrey. Pp. 258, 34 figures.
No. 67. Landslides in the San Juan Mountains, Colorado,
including a consideration of their causes and their classification ;
by Ernest Hower. Pp. 58; 20 plates, 4 figures.
Butietins.—No. 341. Contributions to EKeonomic Geology,
1907. Part Il. Coal and Lignite. Marius R. Campseut, Geol-
ogist in charge. Pp. 444; 25 plates, 7 figures. |
No. 385. Briquetting Tests at the United States Fuel-Testing
Plant, Norfolk, Virginia, 1907-8 ; by Cuartes L. Wrieut. Pp.
41; 9 plates.
No. 889. The Manzano Group of the Rio Grande Valley,
New Mexico; by Wiitis T. Lee and Grorer H. Grrry. Pp.
141; 12 plates, 9 figures.
No. 391. The Devonian Fauna of the Ouray Limestone; by
EK. M. Kinpitze, Pp. 60; 10 plates.
No. 392. Commercial Deductions from Comparisons of Gaso-
line and Alcohol Tests on Internal-Combustion Engines; by
Rospert M. Strone. Pp. 37.
No. 393. Incidental Problems in Gas-Producer Tests; by
R. H. Fernarp, C. D. Smiru, J. K. Ctement and H. A. Grine.
Pp. 27; 8 figures.
No. 895. Radioactivity of the Thermal Waters of Yellow-
stone National Park; by Herman ScuLunpT and Ricuarp B.
Moorr. Pp. 35; 4 plates, 7 figures.
No. 399. Results of Spirit Leveling in West Virginia 1896 to
1908, inclusive. Compiled by 8. 8. Gannetr and D. H. Baupwin.
In codperation with the West Virginia State Geological Survey
during 1901 to 1908, inclusive. Pp. 81.
No. 401. Relations between Local Magnetic Disturbances and
the Genesis of Petroleum; by Grorcr F. Becker. Pp. 24;
1 plate. See p. 499.
No. 402. The Utilization of Fuel in Locomotive Practice; by
W.F.M. Goss. Pp. 27, 8 figures.
No. 408. Comparative Tests of Run-of-Mine and Briquetted
Coal on the Torpedo Boat Biddle. Made, with the collaboration
of Lieut. Commander Kenneth McAlpine, U.S. N., and Ensign
J. W. Hayward, U.S. N.; by Wattrer T. Ray and Henry
KREISINGER. Pp. 48; 10 figures. 3
Warer-Suppity Parers.—No. 224. Some Desert Watering
Places in Southeastern California and Southwestern Nevada ; by
Watter C. MENDENHALL. Pp. 98; 4 plates.
No. 227. Geology and Underground Waters of South Dakota ;
by N. H. Darron. Pp. 156 ; 15 plates, 7 figures.
Geology. 559
No. 232. Underground Water Resources of Connecticut ; by
Herpert E. Grecory. With a Study of the Occurrence of
Water in Crystalline Rocks ; by KE. E. Exits. Pp. 200; 5 plates,
31 figures.
No. 235. The Purification of some Textile and other Factory
Wastes; by HERMAN StTaBLeR and GitBerT H. Prarr. Pre-
pared in codperation with Rhode Island State Board of Health.
fp. 76:
ae: 242. Surface Water Supply of the United States, 1907-8.
Part II. South Atlantic Coast and Eastern Gulf of Mexico.
Prepared under the direction of M. O. Lretcuton, by M. R. Harr
and R. H. Botster. Pp. 226; 3 plates, 1 figure. |
2. Indiana—Depariment of Geology and Natural Resources.
Thirty-Third Annual Report. W.S. Buarcuiey, State Geolo-
gist, 1908. Pp. 663, 4 plates, 1 figure. Indianapolis, 1909 (Wm.
B. Burford).—The most extensive chapter in this volume is
devoted to the coal deposits, and is supplementary to the report
-on the same subject issued in 1898 ; it is accompanied by a large
map. It is stated that a conservative estimate puts the amount of
coal in the state at 50 billion tons, of which 14 billion are regarded
as workable under present conditions. In 1907, 13,250,000 tons
were mined, and the rate has increased at about one million tons
per year. Other chapters deal with soil surveys in several coun-
ties, the petroleum industry and that of the natural gas, now
nearly exhausted. Strictly scientific papers are given by KH. M.
Kindle and V. H. Barnett on the Waldron fauna of Southern
Indiana, and by W. L. Hahn on the mammals of the state.
3. Colorado Geological Survey ; R. D. Grorex, State Geol-
ogist. First Report, 1908. 229 pp., 4 maps, 22 pls.—Colorado
has had a state geologist since 1872; an official, however, who
has had no funds at his disposal to car ry on the work, The state
legislature of 1907 established the State Geological Survey with
an appropriation which, though small, has already resulted in
accomplishing important work. The newly appointed State
Geologist, with the cooperation of Professor Patton and a geolog-
ical staff of fifteen men, has completed a report on the “ Main
Tungsten Area of Boulder County,” the “ Montezuma Mining
District of Summit County,” the “ Foothills Formation of Northern
Colorado,” and the “Hahn’s Peak Region, Routt County.” A
topographical map of the state has been compiled and will soon
be issued ; the Survey is engaged in compiling a geological map
of the state which will present the results of all the work done
up to the present time. The plans as outlined for the future
indicate an intelligent appreciation of the needs of the state and
of the opportunity for investigation of important geological
problems. H. E. G.
4. Geological Survey of Michigan.—The Ninth Annual Report
of the State Geologist, ALFRED C. Lang, for the year 1907 has
recently been issued. Also, as part of the same, the following :
560 Scientific Intelligence.
Foundry Sands ; by Heryricnu Rres and J. A. Roszn. Pp.
41-85 ; with 8 figures, 5 plates.
Summary of the Surface Geology of Michigan; by AtFrREp C.
Lane. Pp. 93-143 ; figures 4-17, 7 plates. |
A Biological Survey of Walnut Lake, Michigan ; by THomas
L. Hankinson. With chapters on the Physiography, Geology
and Flora of the Region, by Cuarues A. Davis; and a paper
on the Aquatic Insects of the Lake, by ‘James G. NEEDHAM.
Pp. 155-288. 63 plates, 6 figures.
5. Illinois Geological State Survey. H. Fostmr Barns,
Director.—The Illinois Survey has recently issued Builetin No.
10 on the Mineral Content of [llnois Waters. This has been
prepared, in cooperation with the State Water Survey, by Epwarp
Bartow, J. A. Uppren, 8. W. Parr and Grorce T. Patmer. It
gives an account of the Illinois waters, with analyses from many
localities.
Circular No. 5, on the Mineral Production of Illinois in 1908,
by R. 8. BiaTcu ey, gives the statistics for 1908. It shows that
the coal production in Illinois for 1908 was 47,600,000 tons, a
decrease of 7 per cent from 1907. ‘The iron production also fell
off largely, but in oil there has been a remarkable increase since
1904, when there was no record of oil in commercial quantities.
Rapid development began in 1906, and in 1908 the production
amounted to nearly 34,000,000 barrels; this gives Illinois the
third place among the states of the Union.
6. History, Geology and Statistics of the Oklahoma Oi and
Gas Fields ; by K. RK. Perry and L. L. Hutcuison.—This brief
pamphlet is issued in order to show the present development of
the industries named; a formal report to the Geological Survey
is in process of preparation. Although the youngest state in the
Union, the oil fields of Oklahoma produced, in 1908, nearly
46,000,000 barrels of crude petroleum, more than any of the other
states. California comes second, and Illinois, Texas and Ohio
follow, while Pennsylvania is seventh in the list.
7. Les Variations Periodiques des Giaciers, XIII Rapport,
1907; par Dr. Ep. Bruckner et HE. Murer. Zeitschrift fur
Gletscherkunde, vol. iii, 1909.—An examination of glaciers dur-
ing 1907 shows the following results: In the Central Alps, one
glacier, the Vorab in the Rhine Basin, is increasing; twelve are
marked as possibly increasing; one is stationary; four are probably
decreasing, and fifty certainly decreasing. In the Hastern Alps,
one glacier is probably advancing; one is stationary; twenty-four
are in retreat; while the glaciers of the Italian Alps, of Savoie and
Dauphiné, with one exception show retreat. The only glacier
measured in the Pyrenees was found to be stationary. In Norway,
the glaciers of Jotunheim show a distinct tendency to elongation.
In 1904-05, six were advancing, four were retreating; 1905-06,
seven were advancing, seven were retreating; during the years
1906-07, fifteen were advancing and only three retreating.
Geology. 561
In the Caucasus, Karagom and Bartui are retreating, while
Midagrawin of the Kasbek group is apparently advancing. In
the Pamir, a group of recently explored glaciers show evidences
of retreating, and the Himalaya glaciers show a general retreat
coupled with sudden spasmodic advance on the part of certain
smaller ice lobes. In North America, the Hallett glacier (Colo-
rado) and several of the glaciers on Mount Hood seem to be
advancing. ‘Those of British Columbia are receding and the
Alaska glaciers appear to be retreating, those in the Muir and
Reid inlets being modified by the earthquake of 1909. uH.E.G.
8. Hand Book for Field Geologists; by C. W. Hayzs, Chief
Geologist, Geological Survey. Second edition, thoroughly
revised First thousand. Pp. vili, 159; 18 figures. New York
1909 (J. Wiley & Sons).—This treatise is divided into two parts,
the first dealing with the equipment, instruments and methods of
observation and collection; the second part giving instructions
for special field investigations in petrology, structural geology,
economic geology, etc. The value of the book is vouched for by
its contents and by the name of the author. It should be in the
hands of all young students of geology, and will be found of
assistance to field workers of large experience. H. E. G.
9. A critical summary of Troost’s unpublished manuscript
on the crinoids of Tennessee; by Exvira Woop. Bull. 64, U.S.
Nat. Mus., 1909, pages vii and 1-150, plates 1-15.—In 1849
Louis Agassiz presented before the American Association for the
Advancement of Science a short paper by Gerhard Troost, then
State Geologist of Tennessee, on the fossil crinoids of that state.
“'Troost’s list,’ numbering 85 species, was published in the
Proceedings of the above society, but very little otherwise has
been made known of his studies until now, when the National
Museum does justice as best it can to the distinguished pioneer
in American geology and paleontology.
The manuscript written in 1849 and submitted the following
year to the Smithsonian Institution described 108 species. Miss
Wood here treats 100 forms divided among the cystoids (7),
blastoids (7), crinoids (84), starfishes (1) and echinoids (1). Even
at this late date 39 specific names proposed by Troost will stand,
the remainder having been described by others since 1849. Of
genera, Troost proposed 16, of which 4 stand. Miss Wood pro-
poses 4 new species or new names, and adds many excellent wash
drawings and retouched photographs of her own making. The
author has put a great deal of hard work on the Troost manu-
script to bring it up to date. Weare grateful for this labor of
love, and congratulate her on the excellence of her studies. c.s.
10. Dendroid Graptolites of the Niagaran dolomites at Hamit-
ton, Ontario; compiled by Ray 8. Bassuer, Bull. 65, U.S. Nat.
Mus., 1909, pp. 76, plates 5.—Hamilton, Ontario, has long been
famous for its abundance of dendroid graptolites and they may
be found in many museums, due chiefly to Colonel Charles Coote
Grant. There are now known from this locality the surprising
562 Scientific Intelligence.
number of 52 forms, and it was R. R. Gurley’s intention to mono-
graph these graptolites. The work was left uncompleted and is
now put in good order by Bassler. The geologic horizon appears
to be the lower portion of the Lockport dolomite. But five of the
species are found in lower horizons, four in the Rochester shale
(Dictyonema retiforme, D. polymorphum, Inocaulis plumulosus,
Acanthograptus walkeri) and one in the Upper Clinton ( Cyclo-
graptus rotadentatus). C. 8.
11. A Carboniferous fauna from Nowaja Semlja, collected by
Dr. W. 8S. Bruce; by G. W. Lex. Trans. Royal Soc. of Edin-
burgh, 47, 1909, pp. 143-186, pls. 1, 2.—From a bed of limestone
(Cape Cherney) on the west coast of southern Nova Zembla, in
lat. 70° 49’ and long. 56° 87’ was collected a most interesting
fauna of over 90 species. These are of the Productus giganteus
horizon, here rich in brachiopods, foraminifers (7 species), corals
and mollusea (dwarfed forms). No cephalopods are present. The
fauna is “very closely allied to that of the Giganteus zone of the
Urals and Central Russia, which is practically the same as that of
Western Europe.” Carruthers studied the corals and in regard
to the horizon states that it is ‘‘ between the base of the Upper
Carboniferous and the top of the Lower Carboniferous of the
Russian classification.” C.St
12. Vorldufige Mitteilung tiber das genus Pseudolingula; von ~
A. Mickxwirz. Bull. ?Acad, Imp. Sci. St. Petersbourg, 1909; pp.
765-772.—The author shows that Lingula quadrata, occurring at
ire. il, iG. 2.
On \) -
SE can QQ AA
~SaxX ==
= =
Ficurrs: 1, 2, schematic drawing of the internal characters of L.
quadrata. After Mickwitz. 1 ventral, 2 dorsal views: occl. ant.,
post.=occlusor anterior, posterior; ob/. int., ext., med.=obliquus internus,
externus, medius; lat.—lateralis; st.=pedicle; st. can.=pedicle canal;
st. f.=pedicle groove; st. nerv.=pedicle nerve.
the top of the Estlandian Ordovician, has a pedicle groove and a
pair of umbonal muscles instead of a single muscle and no groove
Geology. 563
asin Lingula. Pseudolingula (new) is therefore still closely related
to Obolus in its pedicle characters. He also thinks the same
features are present in ZL. lesuweuri and L. rounaultéi of the Silurian.
The reviewer has looked over his collection of Lingulas and
thinks that the characters of Pseudolingula may also be present
in L. cincinnatiensis, L. iowensis and L. lewissi. ‘The preserva-
- tion, however, is not good enough to determine conclusively the
point in question. te Se
13. History of the Clay- Working Industry in the United
States ; by Hernricu Ries and Henry Leieuron. First edition.
First thousand. Pp. viii, 270; 8 plates, 3 figures. New York,
1909 (J. Wiley & Sons).—The senior editor of this volume pub-
lished, some years since, a work on the occurrence and use of clays
in the United States (see vol. xxiii, p. 71). The present work is
more comprehensive and historical and gives an account of the
way in which this industry, one of the earliest to be developed in
this country, has grown to its present magnitude. It may not be
appreciated that the value of clay products in 1906 attained the
total—a maximum thus far—of $161,000,000. Among the differ-
ent states Ohio has for many years occupied the first place with
$30,000,000 of products, and Pennsylvania the second with
$20,000,000 ; New Jersey, Illinois and New York come next in
order. This work will be found to contain many interesting
facts by those concerned with the subject with which it deals.
14. Hlements of Mineralogy, Crystallography and Blowpipe
Analysis from a practical standpoint: by ALFRED J. Moses and
Cuartes Larurop Parsons. Fourth edition, pp. 448, with 583
figures. New York, 1909 (D. Van Nostrand Company).—This
useful work, first issued in 1895, has now reached its fourth edi-
tion, with numerous additions and improvements. Some new
details have been added, and the statistics of production, which:
form a valuable feature, have been brought up to date.
TU. MisceLttanetovus Screntiric INTELLIGENCE.
1. National Academy of Sciences.—The autumn meeting of
the National Academy was held at Princeton, N. J., on Nov. 16-
18. The meeting was largely attended and the hospitality of the
university authorities made the occasion a memorable one. The
sessions were held in the new Arnold Guyot Hall and in part also
in the Palmer Physical Laboratory. In the latter place a lecture
was delivered on Tuesday afternoon by Professor W. F. Magie
on the Investigations of Joseph Henry illustrated by Professor
Heury’s own apparatus. There was also an exhibition on Wed-
nesday illustrating recent scientific investigations in the Museum
of Guyot Hall. The titles of papers presented for reading are
given in the following list :
A. AGaAssiz: On the presence of'teeth in Hchinonéus Van Phels.
W. B. Scorr: The geology of South Africa.
E. G. Conkiin: Formative substancesin eggs. The relative sizes of cells
and nuclei. Memoir of W. K. Brooks.
564 Scientific Intelligence.
T. H. Morean: A study of immunity to self-fertilization in Ciona.
D. M. BarRInGER : Meteor Crater, Arizona.
E. F. Suir: Derivatives of tantalum. Some new methods in electro-
analysis.
O. W. RicHarpson : The emission of electricity by hot bodies.
W. M. Davis: The physiography of southeastern Alaska.
E. Huntineton : The Yale expedition of 1909 to Palestine and Syria.
E. S. Morse: The early stages of Acmea.
S. FLExNER: The transmission of epidemic poliomyelitis to monkeys.
A. G. WeEBSTER : The present status of the ether.
E. B. Frost: Examples of recent photographs made at the Yerkes Observa-
tory. Memoirof C. A. Young.
C. D. WatcotTt: The development of Olenellus.
H. F. Osporn : Report of investigations on the correlation of Tertiary and
Quaternary horizons in Europe and North America. The skull of Tyranno-
SaUrus.
H. N. Russetu: The fission of double stars.
S. Paton: The first movements of the vertebrate embryo in relation to
the development of the nervous system.
U. DawueReN: The development of electric tissue in teleost fishes.
F. W. CLarkE : Memoir of Wolcott Gibbs.
2. Carnegie Institution of Washington.—Recent publica-
tions of the Carnegie Institution are given in the following list
(continued from vol. xxvii, p. 367):
No. 85. Index of Economic Material in Documents of the
States of the United States. Illinois, 1809-1904. Prepared for
the Department of Economics and Sociology of the Carnegie
Institution of Washington ; by ApELAIDE R. Hasse. Pp. 393.
No. 104. Cave Vertebrates of America. A Study in Degen-
erative Evolution; by Cart H. EKigenmann. Pp. v, 2413; 29
plates.
No. 107. Contributions to Cosmogony and the Fundamental
Problems of Geology. The Tidal and other Pr oblems ; by T. C.
CHAMBERLIN, F. R. Mouttoy, C. 8S. SuicutEr, W. D. MacMitiay,
Artuur ©. Lunn and Juzivs Streezitz. Pp. iv, 264. Noticed
on p. 188 of this volume.
No. 110. The Absorption Spectra of Solutions of Certain Salts
of Cobalt, Nickel, Copper, Iron, Chromium, Neodymium, Prosco-
dymium, and Erbium in Water, Methyl, Alcohol, Ethyl Alcohol,
and Acetone, and in Mixtures of Water with the other Solvents ;
by Harry C. Jones and Joun A. ANDERSON. Pp. vi, 110; 81
plates. Noticed on p. 78.
No. 111. Snake Venoms. An Investigation of venomous
Snakes with special reference to the phenomena of their venoms;
by Hipevo Nocucur. Pp. xvi, 315; 33 plates.
No. 112. Bursa Bursa-Pastoris and Bursa Heegeri Biotypes
and Hybrids; by GrorcEe Harrison SHULL. Pp. 57; 23 figures
and 4 plates.
No. 113. Distribution and Movements of Desert Plants; by
Vouney M. Spatpine. Pp. v, 144; 31 plates.
No. 114. Studies of Inheritance in Rabbits ; by W. E. CasTLez,
in collaboration with H. E. Watrer, R. C. MuLienrx, and S.
Cogs. Pp. 70, 4 plates.
Miscellaneous Intelligence. 565
No. 117. Studies in Heredity as illustrated by the Trichomes
of Species and Hybrids of Juglans, Oenothera, Papaver, and
Solanum ; by Witt1am Austin Cannon. Pp. iu), 67; 10 plates,
20 figures.
No. 118. Electrochemical Investigation of Liquid Amalgams
of Thallium, Iridium, Tin, Zinc, Cadmium, Lead, Copper, and
Lithium ; by THEopore Wrtiiam RicwarpDs, with the collabora-
tion of J. Hunt Witson and R. N. Garrop-Tuomas. Pp. 72;
12 figures.
3. Hurvard College Observatory ; Epwarp C. PIcKERING,
Director.—Recent publications are the following (continued from
vol. xxvil, p. 420):
Annats. Vol. LXIV, No. IV. Discussion of the Revised
Harvard Photometry. Pp. 91-146.
No. V. Observations on J. D. 3182 with the 4-inch Meridian
Photometer." Pp. 147-158.
No. VI. Magnitudes of Components ‘of Double Stars. Pp.
159-189.
4, Allegheny Observatory of the University of Pittsburgh. —
Recent publications are the following (see vol. xxvii, p. 420) :
Vol. I, No.15. The Orbit of 7* Orionis.; by Roperr H. BaxeEr.
Pp. 107=111.
No. 16. The Radial Velocities of Four Stars in Taurus ; by
Frank C.Jorpan. Pp. 113-4. |
No. 17. The. Orbit of @’ Lyre; by Frank C. Jorpan. Pp.
ita—118:
No. 18. The Longitude and the Latitude of the New Alle-
gheny Observatory ; by FRanK ScHLEsINGER. Pp. 119-20.
No.19. Five New Spectroscopic Binaries ; by FRANK SCHLEs-
INGER. Pp. 121-22.
5. Museum of the Brooklyn Institute of Arts and Sciences.—
The following have recently appeared : Science Bulletin, Vol. I,
No. 16.—New Birds trom the Orinoco Region and from Trinidad ;
by Grorce K. Cuerriz. Pp. 387-390.
6. The Story of the Comets simply told for general readers ;
by GzorcE F. Cuampers. Pp. xii, 256; 106 figures. Oxford,
1909 (Clarendon Press).—A popular treatise based on the chap-
ters on comets in the author’s well-known Handbook of Astron-
omy, much enlarged and embodying the latest facts and theories.
The work is characterized by the same merits as the other popu-
lar treatises of this author, and it is so abundant in details and so
well classified as to form a useful book of reference for the work-
ing library of an astronomer. Ww. B.
7. Mars et ses Canaux. Les Conditions de Vie. Traduit de
VAnglais par Marcrent Moyen. Pp. 366 with 64 figures. Paris,
1909 (Mercreve de France).—Whatever may be thought of the
work of Percival Lowell, whether the phenomena on the surface
of Mars which he describes are facts or the product of auto-sug-
gestion, there is no difference of opinion as to his sincerity, his
singleness of purpose and his keenness of vision and fertility of
invention ; so that his laborious researches deserve the wide-
566 Scientifie Intelligence.
spread interest which his attractive presentation of them excites.
Professor Moyen’s excellent translation will bring the subject at
first hand to a large number of intelligent critics, most of whom
will probably feel half persuaded that Mars is inhabited by intel-
ligent beings. W. B.
8. Manual for Engineers ; compiled by Cuas. EK. FrErris.
Published by University of Tennessee, Knoxville. Pp. 246.—
The tables in this little volume contain valuable statistics in a
wide range of subjects, from pure mathematics to engineering
and various matters connected with business. In addition to the
obvious useful features of such a work its compilation has been
carried out with a view to influence leading men in the south and
to show the value of a technical education as a means of develop-
ing the natural resources.
9. Wood Turning. Prepared for the use of students in
Manual Training High Schools, Technical Schools and Colleges;
by GrorGE ALEXANDER Ross. Pp. 76; 93 figures, 6 plates.
Boston, 1909 (Ginn & Co.).—This is a practical work on the sub-
ject of wood-turning, with instructions concisely and clearly
stated, and numerous excellent illustrations. .
10. Sir Joseph Banks: “ The Father of Australia”; by J. H.
MaipEN, Government Botanist of New South Wales. Pp. xiv,
244. 64 illustrations. 1909. Sydney (W. A. Gullick) and
London (Kegan Paul, Trench, Triibner & Co.).—This is an inter-
esting account of an Englishman whose work for geographical
exploration and science has had a wide influence on the develop-
ment of his country. He was born in London in 1743 and died
in 1820. He is known chiefly as a traveler, in addition to other
notable voyages, having accompanied Capt. Cook on his first
voyage in 1768-71, when New South Wales was discovered. His
part in connection with this discovery, and also as a patron of
early Australian exploration and colonization, have won him the
title of ‘“‘ The Father of Australia.” He was actively interested
in science, and his botanical collections formed the foundation of
the General Herbarium of the British Museum; his name has
been given to a number of well-known species. He was also a
patron of the arts and in other ways gave the world the benefit
of his rare energy, ability and high character.
11. Americun Association for the Advancement of Science.—
The sixty-first meeting of the American Association will be held
in Boston during the week beginning December 27, under the
presidency of President David Starr Jordan. This is the regular
convocation-week meeting—the eighth of the series—when the
sessions of the Association take place simultaneously with those
of a large number of affiliated societies. A preliminary circular
has already been issued by the Permanent Secretary, Dr. L. O.
Howard, of the Smithsonian Institution, Washington, from whom
further information may be obtained.
It is expected that the Association will visit the Hawaiian
Islands in the summer of 1910 and hold the following convocea-
tion-week meeting in the twin cities of Minneapolis and St. Paul.
PND EX. TO.: VOLUME. xx VITT*
A
Academy, National,
Princeton, 563.
Agassiz, A., teeth in Echinonéus
Van Phels, 490.
Alaska, geological section at Cape
Thompson, Kindle, 520.
Allegheny Observatory,
tions, 565.
Alpha-rays, retardation by metals,
Taylor, 357.
Andes, Central, physiography of,
Bowman, 197, 378.
Arisaig, Nova Scotia, Silurian sec-
tion at, Twenhofel, 143.
Arizona minerals, Blake, 82.
Arnold, R., rocks from the Olympic
Mts., Washington, 9. |
Association, American, Boston meet-
ing, 566. |
— British, meeting at Winnipeg, 412.
Austrian Society of Engineers, prizes,
8
meeting at
publica-
Avogadro, Works of, 87.
B
Banks, Sir Joseph, Maiden, 566.
Barton, E. H., Text-book of Sound,
ve
Bateson, W.,
Heredity, 84.
Bering Sea ice flows, diatomaceous |
dust on, Kindle, 175.
Blake, W. P., Minerals of Arizona, |
82.
Bosworth, R. S., iodometric deter- |
mination of silver, 287.
Mendel’s Principles of
BOTANY.
_ Autogamie bei Protisten, Hart- |
mann, 506. |
Gray Herbarium, publications, 85.
Zoocécidies des Plantes d’Europe, |
Houard, 506. |
Bowles, O., pyromorphite
British Columbia, 40.
Bowman, I., physiography of the |
Central Andes, 197, 373.
from |
Bradley, W. M., analysis of nep-
tunite, California, 15.
British Museum catalogues, 507. .
Brooklyn Institute, publications, 87,
565.
Browning, P. E., precipitation of
tellurium dioxide, 112; complexity
of tellurium, 347.
Buschman, J. O. F., das Salz, etc., 83.
Butler, B. S., pyrogenetic epidote,
27.
Cc
Cady, W. G., electric arc between
metallic electrodes, 89, 289.
Canada geol. survey, 80.
Carnegie Institution of Washington,
list of publications, 064.
Ceylon, mineral survey report, Par-
sons, 81
Chamberlin, T. C.,
ena, 188.
Chambers, G. F.,
ets, 0605.
Chemical Analysis,
McGregory, 504.
tidal phenom-
Story of the Com-
Sellers, 504 ;
CHEMISTRY.
Alumina with silica, etc:, binary
systems of, Shepherd and Rankin,
293 ; optical study, Wright, 315.
Antimony and tin, separation,
Panojotow, 75.
Carbon, fusion in the singing arc,
La Rosa, 598.
Chlorine, determination,
and Read, 044. |
Cuprous sulphate, Recoura, 74.
Hydrochloric acid, decomposition,
Gooch and Gates, 435.
Hydrogen antimonide, action upon
dilute silver solutions, Reckleben,
7A.
Iodides and free iodine, determi-
nation, Bugarsky and Hovrath,
408.
Iodine, determination
Gooch and Perkins, 33.
Gooch
of free,
* This Index contains the general heads. BoTANY, CHEMISTRY (incl. chem. physics),
GEOLOGY, MINERALS, OBITUARY, ROCKS, ZOOLOGY, and under each the titles of Articles
referring thereto are mentioned.
568
CHEMISTRY—cont.
Lead and silver compounds, heat
of formation, Colson, 76.
Metals, boiling points, Greenwood,
508.
Silver, iodometric determination of,
Bosworth, 287.
Sodium aium, Smith, 558.
Sulphuric acid, purification by
freezing, Morancé, 75.
Tellurium, complexity of, Brown-
ing and Flint, 347.
— dioxide, Browning and Flint,
112.
Titanium, niobium, etc., separation,
Weiss and Landecker, 493.
— solutions, peroxidized, Merwin,
119
Trisodium
orthophosphate, etc.,
Mixter, 108.
Chemistry, Kahlenberg, 494; Ost-
wald, 495 ; Ostwald and Morse, 495.
— Outlines, Fenton, 554.
— Physical, Ewell, 555.
— Physiological, Long, 555.
Clay-Working Industry in the U.5.,
Ries and Leighton, 5653.
eee production in 1908, Parker,
00.
Coast Survey, United States, publica-
tions, 86
Cockerell, T. D. A., Tertiary insects.
No. vii, 288; Eocene fossils from
Green River, Wyoming, 447.
Colorado geol. survey, 559.
saa eue from Florissant, 126, 283,
30.
Comets, Story of, Chambers, 565.
Cook, H. J.. New Proboscidean from
Nebraska, 183; Pliocene fauna
from Nebraska, 500.
Culler, J. A., Physics, 357.
D
Dana, E. S., Second Appendix to the
System of Mineralogy, 196.
Darwin and Modern Science, Seward,
505.
Declination instrument,
Hutchins, 260.
Dresser, J. A., a rare rock type from
Canada, 71.
Duff, A. W., Physics, 556.
new,
Ei
Electric arc, between metallic elec-
trodes, Cady and Vinal, 89; Cady,
209.
INDEX.
Electricity excited by the fall of
mercury through gases, Becker, 496.
— Sound and Light, Millikan and
Mills, 79.
Blecieas, initial velocities of, Hull, *
Elektrotechnik, Heinke, 79.
Engineers Manual, Ferris, 566.
Erblichkeitslehre, Elemente
exakten, Johannsen, 85.
Eu eede American, bulletin, 34,
der
Euler, Works of, 88.
Ewell, A. W., Physical Chemistry,
505.
Expansion coefficient, method of
determining, Williams, 180.
F
Fenton, H. J. H., Chemistry, 554.
Ferris, C. E., Manual for Engineers,
566.
‘| Flint, W. R., precipitation of tel-
lurium dioxide, 112; complexity of
tellurium, 347.
Florissant fossils, see Colorado.
Fossils, see Geology.
Ford, W. E., mineral notes, 185;
Second Appendix to Dana’s Miner-
alogy, 196.
G
Garrett, A. E., Periodic Law, 554.
Gases, Viscosity, Zemplen, 496.
Gates, F. L., decomposition of
hydrochloric acid, 438.
GEOLOGICAL REPORTS.
Canada, 80.
Colorado, 559.
Illinois, 560.
Indiana, 559.
Michigan, 559.
New Jersey, 499.
New Zealand, 81.
United States, publications, 89, 557.
West Australia, 81.
West Virginia, 498.
Geologists, Handbook, Hayes, 561.
GEOLOGY.
Arthrodires, American, Hussakof,
411
Camptosaurus, osteology, Gilmore,
410
Carboniferous fauna from Nova
Zembla, Lee, 562.
INDEX.
GEOLOGY— cont.
Carnivora and insectivora of the
Bridger Basin, Matthew, 500.
Cat, skull, etc., of an extinct, Mer-
riam, 501. '
Coleoptera, new fossil from Floris-
sant, Wickham, 126.
Crinoids of Tennessee, Troost’s,
Wood, 561.
Dendioid graptolites of the Niag-
aran dolomites, Bassler, 561.
Devonian faunas of Burma, Reed,
410.
Diatomaceous dust on the Bering
Sea ice, Kindle, 175.
Entelodontidz, revision of, Peter-
son, 411.
EKocene fossils, Green River, Wyo- |
ming, Cockerell, 447.
Fish fauna of the Albert shales,
Lambe, 165.
Geological section at Cape Thomp-
son, Alaska, Kindle, 520.
Glaciers, periodic variations, Bruck-
ner and Muret, 560.
Laramie, application of the term,
Peale, 45.
Miocene drum fish, Smith, 275.
Oklahoma oil and gas fields, Perry |
and Hutchinson, 560.
_ Oligocene of the Cypress Hills, Can-
ada, Lambe, 501.
Olympic Mts., geology, Arnold, 9.
Ordovician and Silurian formations
in Illinois, Savage, 509.
Physiography of the Central Andes,
Bowman, 197, 378.
Pleistocene ruminants,
species, Gidley, 412.
Pliocene fauna from Nebraska,
Matthew and Cook, 500.
Proboscidean from the Nebraska
Miocene, Cook, 183.
Procamelus from the Montana Mio-
cene, Gidley, 411.
Pseudolingula, Mickwitz, 562.
Ptilodus, notes on, Gidley, 411.
Queenstown subdivision, geology,
Park, 497.
Silurian section at Arisaig, Nova
Scotia, Twenhofel, 148.
Teleoceras from the Miocene of
Nebraska, Olcott, 403.
two new
Teratornis, a new Avian genus,
Miller, 501.
Tertiary insects of Florissant,
Colo., Wickham, 126; Cockerell,
283 ; Rohwer, 533.
Tidal and other problems, Cham-
berlin, Moulton, et al., 188.
569
Turtles from the Upper Harrison
beds, Loomis, 17.
Voleanic rocks of No. Carolina,
geology, J. E. Pogue, Jr., 218.
Geophysical Laboratory, Washing-
ton, work of, 268, 298, 334, 453,
AT4,
Glaciers, periodic variation, Bruck-
ner and Muret, 600.
Gockel, A., die Luftelektrizitat, 77.
Gooch, F. A.,, determination of
free iodine, 33; decomposition of
hydrochloric acid, 435 ; determina-
tion of chlorine, 544.
Graham, R. P. D., optical proper-
ties of hastingsite, 540.
Gray Herbarium, Harvard Univer-
sity, publications, 85.
H
Hancock, E. L., Mechanics, 78.
Harker, A., Natural History
Igneous Rocks, 503.
Harvard College Observatory, publi-
cations, 565.
Hayes, C. W., Handbook for Field
Geologists, 561.
Heredity, Mendel’s Principles of,
Bateson, 84; work on, Johannsen,
85.
Holland, T. H., Mineral Resources of
India, 196.
Houard, C., les Zoocécidies
Plantes d’Europe, 506,
Hull, A. W., initial velocities of the
electrons, 251. ;
Hutchins, C. C., new declination
instrument, 260; new method of
measuring light efficiency, 529.
Hypsometry, Hayford and Pike, 87.
of
des
I
Iddings, J. P., Igneous Rocks, 502.
Igneous Rocks, Harker, 503;
Iddings, 502.
Illinois geol. survey, 560.
— Ordovician and Silurian for-
mations, Savage, 509.
India, Mineral Resources, Holland,
196.
Indiana geol. survey, 559.
Influence Machines, Schaffers, 79.
Insects, fossil, from Colorado, Wick-
ham, 125; Cockerell, 283 ; Rohwer,
538.
Iron, cementation by charcoal, Guil-
let and Griffiths, 409.
570 INDEX.
J
Jenney W. P., great Nevada meteor
of 1894, 431.
Jones, H. C., absorption spectra of
solutions, 78.
K
Kahlenberg, L., Chemistry, 494.
Kindle, E. M., diatomaceous dust
on the Bering Sea ice, 175; section
at Cape Thompson, Alaska, 520.
Korea, Journeys through, Koto, 504.
L
Lambe, L. M., fish fauna of the
Albert shales, 165.
Larsen, E. S., relation between the
refractive index and density of
crystallized silicates, 263.
Leighton, H., Clay-Working Indus-
try, 563.
Light efficiency, method of meas-
uring, Hutchins, 529.
Long, J. H., PhysiologicalChemistry,
500.
Loomis, F. B., turtles from the
Upper Harrison beds, 17.
Luftelektrizitat, Gockel, 77.
M
Magnetic disturbances and _ the
genesis of petrcleum, Becker, 499.
— properties of Norway iron, Peirce,
Mars et ses Canaux, Lowell—Moyen,
565.
Materia Radiante, La, Righi, 77.
Matthew, W. D., carnivora and
insectivora of the Bridger Basin,
500; Pliocene fauna from Nebraska,
500.
McGregory, J. F., Chemical Analy-
sis, 004.
Mechanics, Hancock, ‘8.
Melting point determination, White,
453 ; methods at high temperatures,
White, 474.
Mendel’s Principles of Heredity,
Bateson, 84.
Merwin, H. E., peroxidized titanium
solutions, 119 ; connellite and chal-
cophyllite, Arizona, 537.
Metallography, Elements of, Rurer,
Mathewson, 554,
Meteorite, Quinn Canyon, Nevada,
Jenney, 481.
Meteorites in the Museum of Nat.
History, Paris, Meunier, 84.
Michigan geol. survey, 559.
Millikan, R. A., Electricity, etc., 79.
Mills, J., Electricity, etc., 79.
Mineral Resources of India, Holland,
196.
— Resources of Virginia, Watson, 82.
— survey of Ceylon, report, Parsons,
Mineralogy, Second Appendix to
Dana’s System, Dana and Ford, 196.
-— etc., Hlements, Moses and Parsons,
583.
MINERALS.
Arizonite, Arizona, 399.
Calamine crystals, Organ Mts., N.
M., 185. Calcite crystals, Kelly’s
Island, Lake Erie, 186. Chalco-
phyllite, Arizona, 537. Connel-
lite, Arizona, 537.
Datolite, New Jersey, 187. Delor-
enzite, Italy, 83.
Epidote, pyrogenetic, Butler, 27.
Georgiadésite, Italy, 83.
Hastingsite, Ontario, 540.
Neptunite, California, 10.
Parahopeite, 84. | Pyromorphite,
British Columbia, 40.
Rinneite, 84.
Taramellite, Italy, 85. Tarbuttite,
84
Minerals of Arizona, Blake, 82.
Mining Congress, American report,
87.
Mixter, W. G., heat of formation of
trisodium orthophosphate, etc., 103.
Monteregian Hills, Canada, rare
rock type, Dresser, 71.
Morse, H. W., Chemistry, 495.
Moses, A. J., Mineralogy, 563.
Moulton, F. R., tidal and other
problems, 188.
N
Nebraska, Pliocene fauna, Cook, 500;
Proboscidian, Cook, 183.
— Teleoceras from the Miocene of,
Olcott, 408,
New Haven, Conn., Lighthouse
granite, Ward, 181.
New Jersey geol. survey, 499.
New Zealand geol. survey, 81.
Nobel prizes in 1906, 507.
O
OBITUARY.
Dohrn, A., 508.
Fletcher, H., 508.
INDEX.
OBITUAR Y—cont.
Johnson, S. W., 292, 405.
Newcomb, S., 196, 290.
Whiteaves, J. F., 508.
Observations Méridiennes, Bouquet, |
506.
Observatory, Allegheny, 565; Har-
vard College, 565.
Oklahoma oil and gas gag ned.
560.
Olcott, T. F., Teleoceras from the
Miocene of Nebraska, 403.
Ostwald, W., Chemistry, 495.
Ostwald’s Klassiker der
Wissenschaften, 507.
P
Palache, C., connellite and chalco-|
phyllite, Arizona, 537.
Palmer, C., arizonite,
titanate, 353.
Parsons, C. L., Mineralogy, 563.
Peale, A. C., application of the term
Laramie, 45.
Peirce, B. O., magnetic properties of
Norway iron, 1.
Periodic Law, Garrett, 554.
Perkins, C. C., determination of free
iodine, 33.
Perret, F. A., Vesuvius, 413.
Petroleum, genesis, Becker, 499.
Phrenology, Spurzheim and Elder,
S8.
ferric meta-
Physics, Duff, 556; Culler, 557.
Pogue, J. E., Jr., mineral notes, 187;
ancient volcanic rocks of No. Caro-
lina, 218.
Positive rays, Wien, 555.
— excitement by ultra-violet light,
Dember, 496.
Psycho-Biologie, Henry, 88.
R
Radio-activity of potassium salts,
Henriot and Vavon, 409.
Radium, absorption of the y-rays by
lead, Taomikoski, 76.
— Chemical action of penetrating
rays, Kernbaum, 408.
—emanation, electric
Debierne, 494.
Rankin, G. R., binary systems of.
alumina with silica, etc., 298.
discharges,
Rays, alpha, retardation by metals, |
Taylor, 357.
— magnetic, etc., Righi,
— positive, Wien, 555.
— — excitement by ultra-violet light,
Dember, 496.
See Réntgen.
hie
Exakten |
~~
571
Read, H. L., determination of chlor-
ine, 544.
Ries, H., Clay-Working Industry, 563.
_Righi, A., La Materia Radiante, 77.
|
| ROCKS.
Ancient volcanic rocks of North
Carolina, Pogue, 218.
- Granite, Lighthouse, near New
Haven, Conn., Ward, 131.
Igneous Rocks, Iddings, 502.
— — Natural History, Harker, 503.
Pegmatite, Massachusetts, Warren,
449,
Rocks from the Olympic Mts.,
Washington, Arnold, 9.
- Yamaskite, related rock, from the
Monteregian Hills, Canada, ae
Rohwer, SAG fossil insects from
| Colorado, 533.
Rurer, R., Elements of
graphy, 504.
Rontgen rays, polarization, Herweg,
76.
Metallo-
— — refraction, Walter and Pohl, 76.
S)
Salet, P., Spectroscopie Astrono-
mique, 5906.
Salt, occurrence, etc., Buschman, 83.
Savage, T. E., Ordovician and Silu-
rian formations in Illinois, 509.
Schaffers,V., Influence Machines, 79.
Sellers, J. F., Chemical Analysis, 554.
| Seward, A. C., Darwin and Modern
Science, 505.
Shepherd, E. S., binary systems of
alumina with silica, etc., 293.
Silicates, relation of refractive index
and density, Larsen, 263.
Smith, B., Miocene drum fish, 275.
Solutions, absorption spectra, Jones
and Anderson, 78.
Sound, Text-book, Barton, 77.
Specific heats of silicates and plati-
num, White, 334.
Spectra of solutions, absorption,
| Jones and Anderson, 78.
| Spectroscopie Astronomique, Salet,
006.
at
| | Taylor, T. S., retardation of alpha-
| rays by metals, 357.
| Twenhofel, W. H., Silurian section
be pat Arisaig, Nova Scotia, 148.
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572 INDEX.
U
United States Coast Survey, publi-
cations, 86.
— — geol. survey, publications, 80,
507.
Vv
Verrill, A. E., new starfishes from
the Pacific, 59.
Vesuvius, characteristics, etc., Per-
ret, 413.
Vinal, G. W,, electric arc, 89.
Virginia, Mineral Resources, Watson,
82.
WwW
Ward, F., Lighthouse granite near
New Haven, Conn., 1381; mineral
notes, 185.
Warren, C. H., pegmatite in the
granite of Quincy, Mass., 449.
Washington, rocks from the Olym-
pic Mts., Arnold, 9.
Water, decomposition of, Kernbaum,
404). ;
Watson, T. L., Mineral Resources
of Virginia, 82.
Waves, resistance due to obliquely
moving, Rayleigh, 495. 9
West Australia geol. survey, 81.
West Virginia geol. survey, 498. _
White, W. P., specific heats of sili-
eates and platinum, 334; melting
point determination, 453; melting
‘point methods at high tempera-
tures, 474.
Wickham, H. F., new fossil coleop-
tera from Florissant, 126. —
Williams, S. R., method of deter-
ae coefficients of expansion,
180. .
Wood-Turning, Ross, 566.
Wright, F. E., optical study of
compounds of alumina with silica,
ete., 315.
Wyoming, Hocene fossils, Cockerell,
447,
J;
ZOOLOGY.
Hehinonéus, teeth of, Agassiz, 490.
Lepidoptera Phalzene in the Brit-
ish Museum, Catalogue, Hamp-
son, 507.
Starfishes from the Pacific coast,
new, Verrill, 59.
New Circulars.
84: Eighth Mineral List; A descriptive list of new arrivals,
rare and showy minerals. :
85: Minerals for Sale by Weight: Price list of minerals for
. blowpipe and laboratory work.
86: Minerals and Rocks for Working Collections: List of
common minerals and rocks for study specimens; prices
from 1% cents up.
Catalogue 26: Biological Supplies: New illustrated price list
of material for dissection; study and display specimens;
special dissections; models, etc. Szxth edition.
Any or all of the above lists will be sent free on request. We are
constantly acquiring new material and publishing new lists. It pays to
be on our mailing list.
-Ward’s Natural Science Establishment
76-104 Cottece Avz., Rocuester, N. Y.
Warns Naturat Science EstaBlisHMENT
A Supply-House for Scientific Material.
Founded 1862. Incorporated 1890.
DEPARTMENTS:
Geology, including Phenomenal and Physiographic.
Mineralogy, including also Rocks, Meteorites, etc.
Palaeontology. Archaeology and Ethnology.
Invertebrates, including Biology, Conchology, ete.
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Human Anatomy, including Craniology, Odontology, etc.
Models, Plaster Casts and Wall-Charts in all departments.
Circulars in any department free on request; address
Wards Natural Science Establishment,
76-104 College Ave., Rochester, New York, U.S. A.
.
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CONTENTS.
Art. XLVI.—Ordovician and Silurian For mations in Alex- |
ander County, Illinois; by T. EH SavAgwi2 . See 509 —
-XLVIIL —Section at Cape Thompson, Alaska; by E. M.
KinpLE 2) oe ee 520
XLIX.—New Method of Measuring Light Efficiency; by
C Op Mure nse... sane es 529
L.—Three New Fossil Insects from Florissant, Colorado; by
S. A. ROWER ooo tlc ol
LI.—Connellite and Chalcophyllite from Bisbee, Arizona; by
C; PaLacuH and H: E, Muriwin .- 52) 2) eee 537
-LII.—Optical Properties of Hastingsite from Dungannon,
Hastings County, Ontario; by R. P. D. Granam_____. 540.
LIll.—Electrol ytic Determination of Chlorine in Hydro-
chioric Acid with the Use of the Silver Anode; by F. A.
Goocw-and Hi: L. Rap: 25 2.2 222
SCIENTIFIC INTELLIGENCE.
Chemistry and Physies—Boiling Points of Metals, H. C. GREENWooD:
Sodium Aluin, W. R. Smita, 503.—The Elements of Metailography, Dr.
R. Rurer: Outlines of Chemistry with Practical Work, H. J. H. Fanron:
An Elementary Treatise on Qualitative Chemical Analysis, J. FE. SELLERS ;
A Manual of Qualitative Chemical Analysis, J. ¥. McGrecory: The
Periodic Law, A. E. Garrett, 554.—A Text-Book of Physical Chemistry,
Theory and Practice, A. W. EwELi: A Text-Book of Physiological Chem-
istry, J. H. Lone: Positive Rays, W. Wien; Apparent Fusion of Carbon
in the Singing Arc and in Sparks, M. La Rosa.—Determination of ¢/m,
. Wouz: Spectroscopie Astronomigue, P. SALET: Text-Book of Physics,
. W. Dorr, 556.—General Physics : Mechanics and Heat, J. A. CULLER,
Oo7.
Geology—Publications of the United States Geological Survey, G. O. Smize,
557.—Indiana, Department of Geology and Natural Resources ; Thirty-
Third Annual Report, W.S. BuatcHtEy: Colorado Geological Survey,
Be, ees: Geological Survey of Michigan, A.C. Lanz, 059,.—Illinois
Geological State Survey, H. F. Bains: History, Geology and Statistics of
the Giiskeaes Oil and Gas Fields, EK. R. Perry and L. L. Hurcnison ;
Les Variations Periodiques des Glaciers, XIII Rapport, 1907, Ep. Brucx-
NER et E. Murer, 560.—Hand Book for Field Geologists, C. W. Hayes: —
Crinoids of Tennessee, i. Woop: Dendroid Graptolit es of the Niagaran
dolomites at Hamilton, Ont., R. S. BassLter, 561.—Carboniferous fauna
from Nowaja Semlja, G. W. ‘LEE : Vorliufize Mitteilung uber das genus
Pseudolingnla, A. Mickwitz, 562.—Clay-Working Industry in the United
States, H. Rims and H. LEIGHTON: Elements of Mineralogy, Crystaliography
and Blowpipe Analysis, A. J. Moses and C. L. Parsons, 963.
Miscellaneous Scientific Intelligence—National Academy of Sciences, 563.—
Carnegie Institution of Washington, 564.—Harvard College Observatory,
E. C. Pioxerine : Allegheny Observatory of the University of Pittsburgh:
Museum of the Brooklyn Institute of Arts and Sciences : The Story of the
Comets, G. F. CHAmBERS: Mars et ses Canaux; Les Conditions de Vie,
LowELL-Moyrn, 565.—Manual for Engineers, C. E. Ferris: Wood
Turning, G. A. Ross ; Sir Joseph Banks, “The Father of Australia,” J. H.
Maipzn: American Association for the Advancement of Science, 566.
InDEX, 567.
Page | fF
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